ASVAB Test / Guides
ASVAB cheat sheet
The facts behind the questions, grouped by subtest
The big five: percent change divides by the original, work rates add (never the times), V = I × R, a lever balances when weight × distance match, and a² + b² = c² in every right triangle.
General Science
Topic What to know Cell's power plant The mitochondria: they run cellular respiration, turning glucose and oxygen into usable energy (ATP). Photosynthesis formula Carbon dioxide + water + sunlight → glucose + oxygen. Plants take in CO2 and release O2. Which blood cells carry oxygen? Red blood cells, using the iron-rich protein hemoglobin. White cells fight infection; platelets clot. Planet order from the Sun Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Venus is the hottest. Water cycle steps Evaporation (liquid → vapor), condensation (vapor → clouds), precipitation (rain or snow), collection. Newton's three laws 1: inertia — motion resists change. 2: F = ma. 3: every action has an equal and opposite reaction. The pH scale 0–14. Below 7 is acid, 7 is neutral (pure water), above 7 is base. Stomach acid ≈ 2; bleach ≈ 13. Three ways heat moves Conduction (contact, metal spoon), convection (moving fluid, boiling pot), radiation (waves, sunshine). Water's freeze and boil points Freezes at 0 °C / 32 °F; boils at 100 °C / 212 °F at sea level.
Arithmetic Reasoning
Topic What to know Find a percent of a number Turn the percent into a decimal and multiply: 30% of 240 = 0.30 × 240 = 72. 10% first makes it mental math. Percent change formula (new − old) ÷ old × 100. Always divide by the ORIGINAL value. Distance, speed, time triangle d = s × t. So s = d ÷ t and t = d ÷ s. Keep units matched before multiplying. Two workers together Add rates, not times: 1/a + 1/b jobs per hour. Painters taking 6 h and 3 h finish together in 2 h. Average (mean) Total ÷ count. To find a needed score: required average × count − points so far. Splitting by a ratio Add the ratio parts, divide the total by that sum, multiply back. 5:4 with 27 people → 9 parts of 3. Simple interest I = principal × rate × time. $1,200 at 5% for 2 years → 1200 × 0.05 × 2 = $120. Supplies: round up or down? Covering a need (boxes, buses, cans of paint): always round UP. Asking what fits: round DOWN. 20% off, then 10% off Multiply, never add: price × 0.80 × 0.90 = 72% of original — not 70%.
Word Knowledge
Topic What to know Abate To lessen or die down: the storm abated. Think of beating something down to a lower level. Candid Honest and direct, even when uncomfortable. A candid photo catches people as they really are. Prefix: pre- Before. Preflight = before flight; preliminary = before the main event. Root: port Carry. Portable (can be carried), transport (carry across), export (carry out). Adverse vs. averse Adverse = unfavorable (adverse weather). Averse = a person's dislike (averse to risk). Imminent vs. eminent Imminent = about to happen (imminent storm). Eminent = famous and respected (eminent scientist). Frugal Careful with money and resources; thrifty, as praise. Opposite of wasteful. Vigilant Keeping careful watch for danger. From Latin 'vigil,' to stay awake. Root: dict Say or speak. Predict (say before), dictate (speak orders), verdict (truth spoken).
Paragraph Comprehension
Topic What to know Finding the main idea Ask: what do ALL the sentences support? A right answer covers the whole passage, not one detail. Detail question trap The wrong answer is usually the detail sitting NEXT to the asked one. Answer word-for-word from the text. What counts as an inference A conclusion the passage supports but never states. If it needs outside knowledge, it's wrong. Reading tone Watch the loaded words: 'hardly', 'so-called', 'at last'. They reveal skepticism, approval, or regret. The overstatement trap Options with 'always', 'never', or 'should be banned' usually overstate a modest claim. Match strength.
Mathematics Knowledge
Topic What to know Pythagorean theorem a² + b² = c² in right triangles. Memorize triples: 3-4-5, 5-12-13, and their multiples. Complementary vs. supplementary Complementary = 90° (Corner). Supplementary = 180° (Straight). Vertical angles are equal. Triangle angle sum Always 180°. Any polygon: (n − 2) × 180° — hexagon 720°. Circle formulas Circumference = 2πr or πd. Area = πr². Area uses radius SQUARED. Exponent rules xᵃ·xᵇ = xᵃ⁺ᵇ. (xᵃ)ᵇ = xᵃᵇ. x⁰ = 1. x⁻ᵃ = 1/xᵃ. FOIL (x+a)(x+b) = x² + (a+b)x + ab. Middle term adds, last term multiplies. Difference of squares a² − b² = (a + b)(a − b). Spot it whenever a square subtracts a square. Mean, median, mode Mean = average. Median = middle of the SORTED list. Mode = most frequent value. Probability basics Favorable ÷ possible. Independent events multiply: two heads = 1/2 × 1/2 = 1/4. Dividing fractions Flip the second and multiply: 3/4 ÷ 1/2 = 3/4 × 2 = 3/2. Mixed numbers: make improper first.
Electronics Information
Topic What to know Ohm's law V = I × R. Volts push, amps flow, ohms resist. Cover the one you want in the V-I-R triangle. Electrical power P = V × I (watts). Also P = I²R. Energy billed in kilowatt-hours = kW × hours. Series vs. parallel Series: one path, same current, resistances add. Parallel: same voltage, total resistance drops. AC vs. DC DC flows one way (batteries). AC reverses 60 times/second in the US (outlets). Rectifier: AC → DC. US wiring colors Black (or red) = hot. White = neutral. Green or bare copper = ground. Component jobs Resistor opposes. Capacitor stores charge. Inductor stores magnetism. Diode = one-way. Transformer = AC volts up/down. Fuse vs. breaker Both open the circuit on overcurrent. A fuse melts once; a breaker resets. They protect the wiring. Conductors and insulators Best conductors: silver, copper, gold. Insulators: rubber, glass, dry wood. Semiconductor: silicon. Wire gauge (AWG) Smaller number = thicker wire = more current. 10-gauge carries more than 14-gauge.
Auto Information
Topic What to know Four-stroke cycle Intake, compression, power, exhaust — 'suck, squeeze, bang, blow.' Starter vs. alternator Starter drains the battery to crank the engine. Alternator recharges it while the engine runs. Cooling system parts Water pump circulates coolant; thermostat gates it; radiator dumps the heat to air. Exhaust smoke colors Blue = burning oil. White and sweet = coolant (head gasket). Black = too much fuel. Gas vs. diesel ignition Gas: spark plug ignites the mix. Diesel: compression heat ignites injected fuel — no spark plugs. The differential Lets driven wheels spin at different speeds in turns while sharing engine torque. Timing belt Locks camshaft (valves) to crankshaft (pistons). If it snaps, valves can meet pistons. Red oil-pressure light Stop NOW and shut off the engine. No oil pressure destroys an engine in minutes. Disconnecting a battery Remove negative (ground) first, reconnect it last — a slipped wrench then can't spark.
Shop Information
Topic What to know Rip vs. crosscut saw Rip cuts ALONG the grain with chisel teeth; crosscut cuts ACROSS with knife-point teeth. Tap vs. die Tap cuts threads INSIDE a hole; die cuts threads on the OUTSIDE of a rod. Solder, braze, weld Solder and braze melt only the filler. Welding fuses the base metals themselves — far hotter. Precision measuring Micrometers and calipers read to 0.001 inch. Tape measures stop near 1/16 inch. Sandpaper grit Higher number = finer. 80 shapes, 220+ finishes. Work coarse to fine. Thread direction Righty-tighty, lefty-loosey — clockwise tightens standard threads, viewed from the head. Ferrous metal Contains iron (steel, cast iron): magnetic, can rust. Copper and aluminum are non-ferrous. Oily rag danger Piled oily rags self-heat and can ignite on their own. Store in a sealed metal can. Pilot hole Drill slightly smaller than the screw's core so threads bite without splitting the wood.
Mechanical Comprehension
Topic What to know Lever classes 1st: fulcrum in middle (seesaw). 2nd: load in middle (wheelbarrow). 3rd: effort in middle (tweezers). Lever mechanical advantage Effort arm ÷ load arm. Balance: weight × distance equal on both sides of the pivot. Pulley mechanical advantage Count the rope sections holding the load. MA 4 = quarter the force, four times the rope. Meshed gears Turn opposite directions. Speed is inverse to teeth: double teeth = half speed, double torque. Hydraulic force Pressure spreads equally: F2 = F1 × (A2/A1). Big piston, big force — but shorter travel. Work and power Work = force × distance. Power = work ÷ time. Same stairs faster = same work, more power. Inclined plane MA = ramp length ÷ height. Longer ramp, less force, same total work. The machine trade-off Machines multiply force only by multiplying distance. Work in ≥ work out, always. Pressure Force ÷ area. Sharp knife: tiny area, huge pressure. Snowshoe: big area, low pressure.
Assembling Objects
Topic What to know AO golden rule Pieces rotate but NEVER mirror. If a shape looks flipped, that option is wrong. Assembly method Count pieces and match the biggest one's longest edge to the outline first. Then fill the rest. Connector method Track ONE labeled point at a time. Eliminate every option that attaches at an unlabeled corner.
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