ASVAB common mistakes
ASVAB · Understand the traps and how to avoid them.
Immediately calculating with the numbers in an arithmetic word problem before defining the unknown or writing an equation, especially on multi-step percent, ratio, and work problems.
Time pressure makes the numbers feel actionable, and mental arithmetic hides an incorrect setup.
What to do instead
Write 'Let x = ...' and one equation with units before calculating; after solving, substitute the answer back into the original sentence to check it.
Choosing a vocabulary answer because the word looks familiar or matches the topic, without checking its part of speech and exact meaning in the sentence.
Quick recognition feels efficient, and distractors are often near-synonyms with the wrong connotation or grammar.
What to do instead
Cover the choices, predict a synonym, label the needed part of speech, then eliminate any choice that does not fit the sentence's meaning and tone.
Selecting a paragraph-comprehension choice that is true in real life or a reasonable inference but is not explicitly supported by the passage.
Prior knowledge and plausible-sounding options pull attention away from the actual text.
What to do instead
For each choice, point to the line or phrase that proves it; if no textual evidence exists, eliminate it and distinguish 'stated' from 'inferred.'
Evaluating expressions such as -3^2 as 9, or canceling terms across a plus sign, for example treating (x+2)/2 as x+1.
Memorized shortcuts and order-of-operations slips replace structural rules under time pressure.
What to do instead
Rewrite with parentheses, show one operation per line, and test with a number; remember exponentiation before negation and never cancel across addition.
Treating current as something 'used up' by each resistor in a series circuit, so later components are assumed to receive less current.
The water-pressure analogy is overextended, and voltage drop is confused with current drop.
What to do instead
Draw the series loop, label the current as the same at every point, compute voltage drops with V=IR, and use KVL to check that drops sum to the source voltage.
Believing higher-octane fuel increases engine power or is required in every engine.
Advertising and the word 'premium' imply superior performance rather than resistance to knock.
What to do instead
Learn octane rating as anti-knock resistance; use the manufacturer-specified fuel and connect high compression ratio or forced induction to higher octane need.
Guessing pulley or lever force by intuition rather than counting supporting strands or lever arms, such as assuming any movable pulley halves the effort.
Visual complexity and missing geometry make mechanical advantage seem obvious when it is not.
What to do instead
Count the rope segments supporting the movable load, compute mechanical advantage as load divided by effort or torque as force times distance, and check units.
Answering general-science items from everyday belief rather than scientific fact, such as 'sound travels faster in air than in water' or 'arteries always carry oxygenated blood.'
Plausible misconceptions are reinforced by casual language and incomplete prior instruction.
What to do instead
Keep a misconception-correction list and, for each fact, state the mechanism, such as denser media transmitting sound faster or the pulmonary artery carrying deoxygenated blood.
Converting decimal hours or mixed units incorrectly, for example treating 1.5 hours as 1 hour 50 minutes or mixing feet and inches in one calculation.
Familiar notation hides the base-60 time system and inconsistent units.
What to do instead
Convert every quantity to one unit before operating, use dimensional analysis, and write each conversion factor as a fraction that cancels unwanted units.
Using diameter instead of radius in circle formulas, or confusing area and perimeter formulas for common shapes.
Formula recall under time pressure and unlabeled diagrams invite substitution errors.
What to do instead
Write the formula first, label radius and diameter on the figure, and check that an area answer has square units while a perimeter answer has linear units.