BOB LBO flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Valid syllogism rule

Two negative premises give no conclusion, and two particular premises give no conclusion. At least one premise must be universal and at least one affirmative for a valid conclusion to follow.

Blood relation notation

Encode each person as male or female plus a generation offset. Chain the statements, then read the required relation from the net offset and gender rather than from the sentence order.

Total from both ranks

If a person ranks nth from the top and mth from the bottom of a row, the total number of persons is n + m − 1, provided the two ranks refer to the same row.

Circular seating, facing centre

When people face the centre of a circle, a person's left-hand neighbour sits clockwise from them. When they face outward, the left-hand neighbour sits anticlockwise.

Assumption validity test

An assumption is valid only if negating it makes the argument collapse. A statement that merely repeats or paraphrases the given statement is not an assumption.

Alphabet position value

Letters carry values A=1 through Z=26. The opposite letter of position p is 27 − p, so A pairs with Z and M pairs with N.

Simple interest formula

Simple interest equals principal × rate × time divided by 100. The principal stays fixed each year, so interest grows linearly with time.

Compound interest formula

Amount equals principal × (1 + R/100)^T, and compound interest is amount minus principal. Interest is added to the principal at each compounding period.

Rule of 72

Money doubles in roughly 72 divided by the annual percentage rate under compound interest. At 12 percent a year, doubling takes about six years.

Successive discount factor

Two successive discounts d1 and d2 give a net price factor of (1 − d1)(1 − d2). The combined discount is always less than d1 + d2.

Train crossing a platform

Time to cross a platform equals train length plus platform length, divided by train speed. A pole or signal post contributes zero extra length.

Upstream and downstream speed

Downstream speed is boat speed plus stream speed, upstream is boat speed minus stream speed. Their ratio fixes the ratio of upstream to downstream times.

Mixture replacement rule

After n replacements of x litres from a container of V litres, the pure component left is initial quantity × (1 − x/V)^n, assuming full mixing each time.

Combination formula

The number of ways to choose r items from n without regard to order is n! divided by r! times (n − r)!. Use permutations instead when order matters.

Combined work rate

If A finishes in a days and B in b days, together they finish in ab/(a + b) days, because their rates 1/a and 1/b add.

One of the plus plural

In the pattern 'one of the + plural noun + who/that + verb', the verb agrees with the plural noun, while the main clause verb agrees with 'one'.

Third conditional structure

An unreal past condition uses if + past perfect in the condition and would have + past participle in the result, as in 'if I had known, I would have come'.

Reported speech tense shift

When the reporting verb is past, shift present to past and past to past perfect. Time and place words also shift: now to then, here to there, tomorrow to the next day.

Prepositions of time

Use in for months, years and long periods; on for days and dates; at for clock times and fixed expressions such as at noon. Use since for a point, for for a duration.

Parallelism in lists

Items joined by and, or, or a series of commas must share the same grammatical form. A noun paired with a clause breaks parallelism and marks the option wrong.

Fundamental Rights placement

Fundamental Rights appear in Part III of the Indian Constitution, Articles 12 to 35. Directive Principles of State Policy occupy Part IV, Articles 36 to 51.

President versus Vice-President election

The President is elected by an electoral college of elected MPs and elected MLAs of states and union territories. The Vice-President is elected by members of both Houses of Parliament only.

RBI establishment facts

The Reserve Bank of India was set up on 1 April 1935 under the RBI Act 1934 and nationalised in 1949. It issues all currency notes except the one-rupee note.

Repo and reverse repo

Repo is the rate at which the RBI lends short-term funds to banks against securities. Reverse repo is the rate at which the RBI absorbs liquidity from banks.

Tropic of Cancer in India

The Tropic of Cancer passes through eight Indian states, and India's Standard Meridian is 82 degrees 30 minutes east, which fixes Indian Standard Time.

NEFT settlement

National Electronic Funds Transfer settles transactions in half-hourly batches and operates around the clock. It has no minimum or maximum amount limit set by the RBI.

RTGS minimum amount

Real Time Gross Settlement processes each transaction individually and in real time. The minimum transfer amount is two lakh rupees, with no upper limit.

UPI and VPA

The Unified Payments Interface is run by NPCI on the IMPS rail. A Virtual Payment Address identifies an account for payments without revealing the account number.

Demand versus time liability

Savings and current deposits are demand liabilities payable on demand. Fixed and recurring deposits are time liabilities repayable only after the agreed period.

Byte and bit relation

One byte consists of eight bits. Storage scales by 1024, so one kilobyte is 1024 bytes and one megabyte is 1024 kilobytes.

RAM versus ROM

RAM is volatile working memory that loses its contents when power is cut. ROM is non-volatile and retains firmware such as the boot instructions permanently.

OSI layer count

The OSI reference model has seven layers. TCP sits at the transport layer, IP at the network layer, and HTTP at the application layer.

Phishing versus Trojan

Phishing tricks a user into revealing credentials through fake messages or sites. A Trojan is malware disguised as legitimate software that executes once installed.