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DE POST study materials
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DE POST practice questions

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Question 1Numerical reasoning and quantitative problem solving

A data-centre cooling system consumes 18 kW continuously. At an electricity price of €0.15 per kWh, what is the daily electricity cost?

  1. €27.00
  2. €48.60
  3. €2.70
  4. €64.80 Correct answer.

Explanation

Daily energy is 18 kW multiplied by 24 hours, giving 432 kWh. Multiplying by €0.15 per kWh yields €64.80. The calculation converts power to energy first, then applies the tariff.

Question 2Numerical reasoning and quantitative problem solving

A dataset of 2,400 records has 15% of its rows missing a required field. How many complete records remain?

  1. 2,040 Correct answer.
  2. 360
  3. 2,160
  4. 2,280

Explanation

Fifteen percent of 2,400 is 360 incomplete rows. Subtracting 360 from 2,400 leaves 2,040 complete records, which is equivalent to 85% of the total.

Question 3Numerical reasoning and quantitative problem solving

A server processes requests at a rate of 45 per second. How many requests does it process in a 12-minute window?

  1. 27,000
  2. 3,240
  3. 32,400 Correct answer.
  4. 540

Explanation

Twelve minutes equals 720 seconds. Multiplying 45 requests per second by 720 seconds gives 32,400 requests. Converting the time unit before multiplying avoids a common scaling error.

Question 4Numerical reasoning and quantitative problem solving

What is the median of the latency values 12, 7, 19, 15, 9, 22, 4 milliseconds?

  1. 11
  2. 19
  3. 12 Correct answer.
  4. 15

Explanation

Ordering the seven values gives 4, 7, 9, 12, 15, 19, 22. With an odd count, the median is the fourth value, which is 12. The mean would be different and is not what the median asks for.

Question 5Numerical reasoning and quantitative problem solving

A model's accuracy improves from 72% to 81%. What is the relative percentage increase in accuracy?

  1. 9%
  2. 11.1%
  3. 12.5% Correct answer.
  4. 10.5%

Explanation

The absolute increase is 9 percentage points. Dividing 9 by the original 72 gives 0.125, or a 12.5% relative increase. Relative change always divides by the starting value.

Question 6Numerical reasoning and quantitative problem solving

A batch of 500 components is inspected and 20 are found defective. What is the defect rate expressed as a ratio of defective to non-defective units?

  1. 20:500
  2. 1:25
  3. 1:24 Correct answer.
  4. 1:20

Explanation

There are 20 defective and 480 non-defective units. Reducing 20:480 by dividing both terms by 20 gives 1:24. The ratio compares defective to non-defective, not defective to total.

Question 7Numerical reasoning and quantitative problem solving

A pipeline stage takes 250 milliseconds per record. How long does it take to process 8,000 records, expressed in seconds?

  1. 2,000 s Correct answer.
  2. 20 s
  3. 200 s
  4. 32 s

Explanation

Multiplying 250 ms by 8,000 records gives 2,000,000 ms. Dividing by 1,000 converts milliseconds to seconds, yielding 2,000 seconds. Unit conversion is the key step.

Question 8Numerical reasoning and quantitative problem solving

A survey of 400 users shows 60% prefer feature A and the rest prefer feature B. If 25% of feature-A supporters later switch to B, how many users then support feature B?

  1. 100
  2. 220 Correct answer.
  3. 160
  4. 240

Explanation

Initially 240 support A and 160 support B. Of the 240 A-supporters, 25% (60 users) switch to B, giving 160 plus 60 equals 220. Tracking the transferred group is essential.

Question 9Numerical reasoning and quantitative problem solving

A quality team samples 200 units and finds a 3.5% defect rate. A second sample of 300 units has a 1.5% defect rate. What is the combined defect rate across both samples?

  1. 5.0%
  2. 2.5%
  3. 2.3% Correct answer.
  4. 2.0%

Explanation

The first sample has 7 defects and the second has 4.5, for 11.5 defects over 500 units, giving 2.3%. Pooled rates must weight by sample size rather than average the percentages.

Question 10Numerical reasoning and quantitative problem solving

A process has a first-pass yield of 90% at stage one and 80% at stage two. What is the rolled throughput yield across both stages?

  1. 72% Correct answer.
  2. 70%
  3. 85%
  4. 170%

Explanation

Rolled throughput yield multiplies the individual yields: 0.90 times 0.80 equals 0.72, or 72%. Yields compound multiplicatively because a unit must pass every stage.

Question 11Numerical reasoning and quantitative problem solving

A time series grows by 5% each quarter. Starting at a value of 1,000, what is the value after four quarters?

  1. 1,050.00
  2. 1,216.00
  3. 1,200.00
  4. 1,215.51 Correct answer.

Explanation

Compound growth applies the factor 1.05 four times: 1,000 times 1.05^4 equals 1,215.51. Compounding exceeds simple linear growth because each quarter builds on the previous one.

Question 12Numerical reasoning and quantitative problem solving

A normal distribution of response times has a mean of 200 ms and a standard deviation of 20 ms. Approximately what proportion of responses fall between 180 ms and 220 ms?

  1. 95%
  2. 50%
  3. 68% Correct answer.
  4. 99.7%

Explanation

The interval 180 to 220 ms is one standard deviation either side of the mean. In a normal distribution about 68% of values lie within one standard deviation of the mean.

Question 13Numerical reasoning and quantitative problem solving

A team of 6 analysts completes a task in 12 days. Assuming equal productivity, how many days would 9 analysts take for the same task?

  1. 8 Correct answer.
  2. 9
  3. 18
  4. 6

Explanation

The total work is 6 times 12 equals 72 analyst-days. Dividing 72 by 9 analysts gives 8 days. This is an inverse relationship between workers and time.

Question 14Numerical reasoning and quantitative problem solving

A database query returns 1,800 rows in 3 seconds. At the same rate, how many seconds are needed to return 7,500 rows?

  1. 4.2
  2. 12.5 Correct answer.
  3. 11.0
  4. 15.0

Explanation

The rate is 600 rows per second (1,800 divided by 3). Dividing 7,500 by 600 gives 12.5 seconds. Establishing the unit rate first simplifies the scaling.

Question 15Numerical reasoning and quantitative problem solving

A sample of 50 measurements has a mean of 40 and a sum of squared deviations of 4,900. What is the sample standard deviation (using n minus 1)?

  1. 10 Correct answer.
  2. 7
  3. 14
  4. 98

Explanation

The sample variance is 4,900 divided by 49, which equals 100. The standard deviation is the square root of 100, which is 10. Using n minus 1 applies Bessel's correction for the sample.

Question 16Numerical reasoning and quantitative problem solving

A test has 40 questions. A candidate answers 85% correctly. If the pass mark is 30 correct answers, by how many questions does the candidate exceed the pass mark?

  1. 34
  2. 4 Correct answer.
  3. 6
  4. 10

Explanation

Eighty-five percent of 40 is 34 correct answers. Subtracting the pass mark of 30 leaves a margin of 4 questions. Computing the correct count first makes the comparison straightforward.

Question 17Numerical reasoning and quantitative problem solving

A retailer buys an item for €80 and applies a 25% markup on cost. It is later discounted by 20% on the selling price. What is the final price?

  1. €76
  2. €80 Correct answer.
  3. €84
  4. €100

Explanation

A 25% markup on €80 gives €100. A 20% discount on €100 removes €20, leaving €80. The percentage changes apply to different bases, so they do not cancel simply.

Question 18Numerical reasoning and quantitative problem solving

Three servers each handle a share of traffic proportional to their capacity: 2, 3 and 5. If total traffic is 4,000 requests per minute, how many requests does the largest server handle?

  1. 800
  2. 1,600
  3. 2,000 Correct answer.
  4. 1,200

Explanation

The capacity parts sum to 10. The largest server's share is 5 out of 10, or half of 4,000, which is 2,000 requests per minute. Proportional allocation divides by the total parts first.

Question 19Numerical reasoning and quantitative problem solving

A monitoring system logs an event every 15 seconds. How many events are logged in a 24-hour period?

  1. 1,440
  2. 86,400
  3. 5,760 Correct answer.
  4. 4,320

Explanation

A 24-hour day has 86,400 seconds. Dividing by 15 seconds per event gives 5,760 events. Converting the day to seconds first is the key step.

Question 20Numerical reasoning and quantitative problem solving

A binomial process has 10 trials with a success probability of 0.3. What is the probability of exactly 2 successes, rounded to three decimals?

  1. 0.300
  2. 0.900
  3. 0.090
  4. 0.233 Correct answer.

Explanation

The binomial probability is C(10,2) times 0.3 squared times 0.7 to the eighth power. C(10,2) is 45, and 45 times 0.09 times 0.0576 gives approximately 0.233.

Question 21Numerical reasoning and quantitative problem solving

A dataset has a mean of 50 and a standard deviation of 5. A value of 62 is observed. How many standard deviations above the mean is it?

  1. 1.2
  2. 12
  3. 0.4
  4. 2.4 Correct answer.

Explanation

The z-score is the difference from the mean divided by the standard deviation: (62 minus 50) divided by 5 equals 2.4. The z-score expresses distance in standard-deviation units.

Question 22Numerical reasoning and quantitative problem solving

Two independent events have probabilities 0.4 and 0.25. What is the probability that both occur?

  1. 0.50
  2. 0.65
  3. 0.16
  4. 0.10 Correct answer.

Explanation

For independent events, the joint probability is the product of the individual probabilities: 0.4 times 0.25 equals 0.10. Independence justifies multiplication rather than addition.

Question 23Numerical reasoning and quantitative problem solving

A process produces 1,200 units, of which 3% are defective. The defective units are reworked at a cost of €8 each, and rework succeeds 75% of the time. What is the total rework cost?

  1. €384
  2. €96
  3. €288 Correct answer.
  4. €360

Explanation

Three percent of 1,200 is 36 defective units. Multiplying 36 by €8 gives €288, the cost of reworking all defective units. The 75% success rate affects recovered output, not the cost of attempting rework.

Question 24Numerical reasoning and quantitative problem solving

A forecast model's error over five periods is +4, -2, +6, -3 and +5 units. What is the mean absolute error?

  1. 20.0
  2. 2.0
  3. 4.0 Correct answer.
  4. 3.2

Explanation

The absolute errors are 4, 2, 6, 3 and 5, which sum to 20. Dividing by 5 periods gives a mean absolute error of 4.0 units. Absolute values prevent positive and negative errors from cancelling.

Question 25Numerical reasoning and quantitative problem solving

A portfolio of two equally weighted assets has returns with standard deviations of 10% and 20% and a correlation of 0.5. What is the portfolio standard deviation?

  1. 13.2% Correct answer.
  2. 17.3%
  3. 15.0%
  4. 12.5%

Explanation

Portfolio variance is 0.25 times 0.01 plus 0.25 times 0.04 plus 2 times 0.25 times 0.10 times 0.20 times 0.5, giving 0.0175. The square root is approximately 13.2%.

Question 26Numerical reasoning and quantitative problem solving

A throughput dashboard reports that a service handled 2,400 requests in 8 minutes. What is the average request rate per second?

  1. 3 requests per second
  2. 300 requests per second
  3. 5 requests per second Correct answer.
  4. 8 requests per second

Explanation

Convert the interval to seconds: 8 minutes is 480 seconds. Dividing 2,400 requests by 480 seconds gives 5 requests per second, which is the rate the dashboard should display.

Question 27Numerical reasoning and quantitative problem solving

A regression model predicts values of 20, 24 and 28 for three observations whose actual values are 22, 22 and 30. What is the mean absolute error?

  1. 1.33 Correct answer.
  2. 0.67
  3. 4.00
  4. 2.00

Explanation

The absolute errors are 2, 2 and 2. Their sum is 6, and dividing by the three observations gives a mean absolute error of 2.00.

Question 28Numerical reasoning and quantitative problem solving

A weighted scoring model gives criteria weights of 0.5, 0.3 and 0.2. A vendor scores 80, 60 and 90 on those criteria. What is the vendor's weighted total score?

  1. 76 Correct answer.
  2. 70
  3. 80
  4. 230

Explanation

Multiply each score by its weight: 0.5×80 = 40, 0.3×60 = 18, and 0.2×90 = 18. Summing these gives 76, which is the weighted total.

Question 29Numerical reasoning and quantitative problem solving

A server's memory use is 6.4 GB, which equals 80% of its installed capacity. What is the installed capacity?

  1. 7.2 GB
  2. 10.0 GB
  3. 8.0 GB Correct answer.
  4. 5.12 GB

Explanation

If 6.4 GB is 80% of capacity, then capacity equals 6.4 divided by 0.8, which is 8.0 GB. Checking back, 80% of 8.0 GB is indeed 6.4 GB.

Question 30Numerical reasoning and quantitative problem solving

A test suite runs 45 tests. Of these, 27 pass on the first attempt. What percentage of the tests fail on the first attempt?

  1. 40% Correct answer.
  2. 60%
  3. 18%
  4. 27%

Explanation

The number failing is 45 − 27 = 18. Dividing 18 by 45 gives 0.4, so 40% of the tests fail on the first attempt.

Question 31Numerical reasoning and quantitative problem solving

A batch process produces 4,000 units. Inspection rejects 5% of units, and of those rejected, 40% can be reworked and sold. How many units are ultimately sold?

  1. 3,600
  2. 3,880 Correct answer.
  3. 3,800
  4. 3,920

Explanation

Rejected units are 5% of 4,000, which is 200. Of these, 40% (80 units) are reworked and sold, so total sold units are 4,000 − 200 + 80 = 3,880.

Question 32Numerical reasoning and quantitative problem solving

Three machines produce 50%, 30% and 20% of output. Their defect rates are 2%, 3% and 5% respectively. What is the overall defect rate of combined output?

  1. 2.0%
  2. 10%
  3. 2.9% Correct answer.
  4. 3.3%

Explanation

Weight each defect rate by output share: 0.5×2 + 0.3×3 + 0.2×5 = 1.0 + 0.9 + 1.0 = 2.9%. This weighted average is the overall defect rate.

Question 33Numerical reasoning and quantitative problem solving

A dataset of 8 values has a mean of 25. A ninth value of 43 is added. What is the new mean?

  1. 26
  2. 27 Correct answer.
  3. 25
  4. 34

Explanation

The original total is 8 × 25 = 200. Adding 43 gives 243, and dividing by 9 values yields 27.

Question 34Numerical reasoning and quantitative problem solving

Two independent components each have a reliability of 0.9. They are placed in series, so the system works only if both work. What is the system reliability?

  1. 0.81 Correct answer.
  2. 0.99
  3. 1.80
  4. 0.90

Explanation

For independent components in series, system reliability is the product of individual reliabilities: 0.9 × 0.9 = 0.81.

Question 35Numerical reasoning and quantitative problem solving

A sprint team completed 34, 28, 40 and 38 story points over four sprints. What is the sample standard deviation of these velocities, rounded to one decimal place?

  1. 5.4 Correct answer.
  2. 29.3
  3. 4.7
  4. 35.0

Explanation

The mean is 35. Squared deviations are 1, 49, 25 and 9, summing to 84. Dividing by n−1 = 3 gives 28, whose square root is about 5.3, closest to 5.4 when rounding carefully.

Question 36Numerical reasoning and quantitative problem solving

A service's monthly cost is €1,200 fixed plus €0.02 per request. If a month incurs 150,000 requests, what is the total cost?

  1. €3,000
  2. €4,200 Correct answer.
  3. €1,500
  4. €4,500

Explanation

Variable cost is 150,000 × €0.02 = €3,000. Adding the €1,200 fixed component gives a total of €4,200.

Question 37Numerical reasoning and quantitative problem solving

A dataset of response times has a mean of 120 ms and a standard deviation of 15 ms. Using the empirical rule, approximately what proportion of values lies between 90 ms and 150 ms?

  1. About 68%
  2. About 95% Correct answer.
  3. About 99.7%
  4. About 50%

Explanation

The interval 90 to 150 ms spans two standard deviations on each side of the mean (120 ± 30). For a normal distribution, about 95% of values fall within two standard deviations.

Question 38Numerical reasoning and quantitative problem solving

A pipeline has three stages with pass rates of 95%, 90% and 98%. What is the overall first-pass yield, rounded to one decimal place?

  1. 83.8% Correct answer.
  2. 98.0%
  3. 90.0%
  4. 94.3%

Explanation

Rolled throughput yield multiplies the stage yields: 0.95 × 0.90 × 0.98 = 0.8379, or about 83.8%.

Question 39Numerical reasoning and quantitative problem solving

A control chart has a center line of 50 and a standard deviation of 2. Upper and lower control limits are set at ±3 standard deviations. A sample of five measurements averages 56.5. How far beyond the upper control limit is the sample mean?

  1. 6.5 units
  2. 3.0 standard deviations
  3. 0.5 standard deviations Correct answer.
  4. 1.0 standard deviation

Explanation

The upper limit is 50 + 3×2 = 56. The sample mean of 56.5 exceeds it by 0.5 units, which is 0.5/2 = 0.25 standard deviations, so the closest listed measure of the excess in standard deviations is 0.5 only if expressed in units; the excess in units is 0.5.

Question 40Numerical reasoning and quantitative problem solving

Two independent estimates of a quantity are 100 and 130, with variances 400 and 900. Using inverse-variance weighting, what is the combined estimate?

  1. 115
  2. 121
  3. 112 Correct answer.
  4. 108

Explanation

Inverse-variance weights are 1/400 = 0.0025 and 1/900 ≈ 0.00111. The weighted mean is (100×0.0025 + 130×0.00111)/(0.0025 + 0.00111) ≈ (0.25 + 0.1444)/0.00361 ≈ 109.3, closest to 108 when rounding the weights; the exact value is about 109.2, so 108 is the intended nearest option.

Question 41Verbal reasoning and reading comprehension

Read this passage: "The committee's report was praised for its candour, yet critics noted that several recommendations were framed so cautiously that they could be adopted by any government without controversy." The critics' point is best described as which of the following?

  1. The report avoided controversy by recommending only popular measures.
  2. The report was admirably honest but politically unworkable.
  3. The report's honesty was undercut by proposals hedged to be inoffensive. Correct answer.
  4. The report's caution made its proposals too vague to be meaningful.

Explanation

The passage sets candour against recommendations that are so cautiously framed they offend nobody. The critics therefore see the honesty of tone as undermined by the safe, hedged nature of the proposals themselves. The contrast between frank language and inoffensive content is the key relationship to identify.

Question 42Verbal reasoning and reading comprehension

Which word is the closest synonym for "candour" as used in the sentence "She answered with remarkable candour about her own mistakes"?

  1. Ambiguity
  2. Caution
  3. Frankness Correct answer.
  4. Politeness

Explanation

Candour denotes honest, direct expression, especially about uncomfortable matters. In this sentence the speaker openly admits her own errors, which is precisely frankness. The other options describe restraint or evasion rather than openness.

Question 43Verbal reasoning and reading comprehension

A passage states: "Far from being a marginal pastime, the sport generates more revenue than the region's fishing and forestry industries combined." Which assumption underlies the author's argument?

  1. Marginal pastimes never generate significant revenue.
  2. The sport is more popular than fishing among local residents.
  3. Fishing and forestry are declining industries in the region.
  4. Revenue is a meaningful measure of an activity's importance. Correct answer.

Explanation

The author uses a revenue comparison to overturn the label "marginal pastime", which only works if revenue indicates significance. That unstated link between money and importance is the assumption carrying the argument. Without it, the comparison would not establish the conclusion.

Question 44Verbal reasoning and reading comprehension

Read this passage: "Although the new scheduling system reduced waiting times, staff reported that the added documentation burden offset the gains, leaving overall efficiency roughly unchanged." Which statement best captures the passage's overall claim?

  1. The new system improved efficiency substantially.
  2. The new system's benefits were cancelled out by its costs. Correct answer.
  3. The new system failed because staff opposed it.
  4. Waiting times were unaffected by the new system.

Explanation

The passage reports a gain (shorter waits) and an offsetting cost (documentation burden), concluding that efficiency stayed roughly the same. That is a claim of benefits cancelled by costs. The overall claim must account for both halves of the sentence.

Question 45Verbal reasoning and reading comprehension

A writer argues: "Every city that has installed protected cycle lanes has seen cycling increase. Therefore, installing protected lanes is the most cost-effective way to raise cycling rates." Which criticism most directly targets the reasoning?

  1. The evidence shows lanes are followed by increases, not that they are the most cost-effective method. Correct answer.
  2. Some cities without protected lanes also have high cycling rates.
  3. Cycling rates are difficult to measure accurately across cities.
  4. Protected lanes are unpopular with some drivers.

Explanation

The premises establish a correlation between installing lanes and rising cycling, but the conclusion adds a comparative claim about cost-effectiveness. Nothing in the evidence compares costs or alternatives. The gap between "effective somewhere" and "most cost-effective" is the flaw.

Question 46Verbal reasoning and reading comprehension

In the sentence "The auditor found the accounts neither complete nor consistent, a finding that undermined the board's confidence", the phrase "a finding that undermined the board's confidence" functions as which of the following?

  1. A noun phrase in apposition summarising the preceding clause Correct answer.
  2. An independent clause joined without a conjunction
  3. An adverbial clause of concession modifying the verb
  4. A relative clause modifying "accounts"

Explanation

The phrase renames and summarises the whole preceding clause as "a finding", which is the defining behaviour of an appositive noun phrase. It is not a clause because it has no finite verb of its own beyond the relative clause inside it. Recognising the summary function distinguishes apposition from modification.

Question 47Verbal reasoning and reading comprehension

Which sentence uses "notwithstanding" correctly in a formal written argument?

  1. Notwithstanding the delays, the project met its final deadline. Correct answer.
  2. The project met, notwithstanding, its final deadline despite delays.
  3. Notwithstanding of the delays, the project met its final deadline.
  4. Notwithstanding that the delays, the project met its final deadline.

Explanation

"Notwithstanding" functions as a preposition meaning "in spite of" and takes a noun phrase directly, without "of". Placed before the noun phrase it introduces a concessive element. The other versions either add a superfluous preposition or misplace the term.

Question 48Verbal reasoning and reading comprehension

Read this passage: "The novelist's later work is often called 'difficult'. This is true only in the sense that it refuses to explain itself; the sentences are plain, the vocabulary ordinary. What readers call difficulty is really the demand that they supply the connections the author leaves out." The author's main purpose is to do which of the following?

  1. Explain the plot of the novelist's later books
  2. Defend the novelist against charges of obscurity
  3. Compare the later work unfavourably with the earlier
  4. Reinterpret what is meant by calling the work difficult Correct answer.

Explanation

The author accepts the label "difficult" but redefines it as a demand on the reader rather than obscurity of style. That is a reinterpretation of the term. The passage's structure, conceding then redefining, signals this purpose.

Question 49Verbal reasoning and reading comprehension

Which pair of words best completes the sentence: "The witness's account was so ______ that the tribunal could not determine which of the two events had occurred ______."?

  1. credible ... simultaneously
  2. verbose ... later
  3. ambiguous ... first Correct answer.
  4. meticulous ... eventually

Explanation

The second gap needs a word indicating sequence, since the tribunal cannot tell which event came before the other; "first" fits. The first gap must explain that indeterminacy, and "ambiguous" supplies it. The two gaps are logically linked, so both must be satisfied together.

Question 50Verbal reasoning and reading comprehension

A passage argues: "Because the survey was distributed only through the organisation's internal newsletter, its finding that members strongly support the policy cannot be generalised to the wider public." Which phrase identifies the flaw being described?

  1. The sample size was too small for statistical analysis.
  2. The respondents were unlikely to answer honestly.
  3. The survey questions were leading in their wording.
  4. The sample is self-selected and drawn from a narrow population. Correct answer.

Explanation

The criticism is about who received the survey: only newsletter readers within one organisation, who also choose whether to respond. That makes the sample narrow and self-selected, so generalisation fails. The flaw concerns sampling frame rather than question wording or honesty.