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OAR Prep

Free tool · OAR Math Skills

OAR math practice test

15 Math Skills questions from the OAR Prep question bank, from rates and ratios to probability. Work them on scratch paper, then check the worked answer.

15 Math Skills questions · about 20 minutes · scratch paper, no calculator. Pick an answer to see whether you’re right and why.

  1. Question 1 of 15 · Math SkillsHaley's violin instructor insists that she practice a minimum of 3.5 hours per week. If she practices 45 minutes on both Sunday and Monday, and 25 minutes on both Tuesday and Wednesday, how many minutes does she have left to practice this week?
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    Answer: A. 70 minutes

    3.5 hours = 210 minutes. She has practiced 45 + 45 + 25 + 25 = 140 minutes, leaving 210 − 140 = 70 minutes.

  2. Question 2 of 15 · Math SkillsSolve for x: 4x − 7 = 21
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    Answer: C. 7

    Add 7 to both sides: 4x = 28. Divide by 4: x = 7.

  3. Question 3 of 15 · Math SkillsWhat is the mean of the numbers 42, 48, 50, 50, and 60?
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    Answer: C. 50

    Sum = 250; divide by the 5 values: 250 ÷ 5 = 50.

  4. Question 4 of 15 · Math SkillsThe sum of two consecutive integers is 47. What is the larger integer?
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    Answer: C. 24

    n + (n + 1) = 47 → 2n + 1 = 47 → n = 23, so the larger integer is 24.

  5. Question 5 of 15 · Math SkillsA circle has a diameter of 10 inches. Using π ≈ 3.14, what is its circumference?
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    Answer: C. 31.4 inches

    Circumference = π × diameter = 3.14 × 10 = 31.4 inches.

  6. Question 6 of 15 · Math SkillsA candidate's five practice scores are 72, 68, 84, 76, and 90. What is the median score?
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    Answer: A. 76

    Order them: 68, 72, 76, 84, 90. The middle value is 76.

  7. Question 7 of 15 · Math SkillsA plane flies 600 miles with a 50 mph tailwind, then returns the same 600 miles into the same 50 mph headwind. Its airspeed in still air is 250 mph. What is the total flight time?
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    Answer: D. 5 hours

    Outbound groundspeed is 250 + 50 = 300 mph, so 600 ÷ 300 = 2 hours. Return groundspeed is 250 − 50 = 200 mph, so 600 ÷ 200 = 3 hours. Total = 5 hours.

  8. Question 8 of 15 · Math SkillsA tank fills in 5 hours through its inlet, but a stuck valve drains a full tank in 20 hours. With both open, how long to fill the empty tank?
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    Answer: B. 6 hours 40 minutes

    Net rate = 1/5 − 1/20 = 3/20 tank per hour, so time = 20/3 hours = 6 hours 40 minutes.

  9. Question 9 of 15 · Math SkillsHow many liters of pure water must be added to 10 liters of a 50% acid solution to dilute it to a 20% acid solution?
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    Answer: A. 15 liters

    The acid stays at 5 L (50% of 10 L). For a 20% solution, 5 ÷ total = 0.20, so the total is 25 L: add 25 − 10 = 15 L of water.

  10. Question 10 of 15 · Math Skills$2,000 is invested at 6% simple annual interest. How much interest accrues after 3 years?
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    Answer: C. $360

    Simple interest = P × r × t = 2,000 × 0.06 × 3 = $360.

  11. Question 11 of 15 · Math SkillsA bag holds 4 red and 6 blue marbles. Two are drawn without replacement. What is the probability that both are red?
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    Answer: B. 2/15

    P(both red) = 4/10 × 3/9 = 12/90 = 2/15.

  12. Question 12 of 15 · Math SkillsThree pens and two notebooks cost $12. Two pens and four notebooks cost $16. What does one notebook cost?
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    Answer: A. $3

    Write 3p + 2n = 12 and 2p + 4n = 16. Halve the second: p + 2n = 8. Subtract it from the first: 2p = 4, so p = $2, and then 2n = 6, so n = $3.

  13. Question 13 of 15 · Math SkillsSimplify: (2³ × 2⁴) ÷ 2².
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    Answer: D. 32

    With the same base, add the exponents when multiplying and subtract them when dividing: 3 + 4 − 2 = 5, so the answer is 2⁵ = 32.

  14. Question 14 of 15 · Math SkillsIn a unit the ratio of officers to enlisted is 1:9. If there are 250 personnel in all, how many are officers?
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    Answer: A. 25

    The ratio 1:9 gives 10 parts in total, so officers = 250 ÷ 10 = 25.

  15. Question 15 of 15 · Math SkillsA fuel tank is 3/4 full. A flight burns 1/3 of the fuel currently in the tank. What fraction of a full tank remains?
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    Answer: D. 1/2

    Burned = 1/3 of 3/4 = 1/4 of the tank. Remaining = 3/4 − 1/4 = 1/2.

What the OAR Math Skills Test covers

The Math Skills Test is one of the three OAR subtests. It covers arithmetic, fractions, percentages, ratios, algebra, geometry and word problems, all without a calculator. Most questions are short word problems, so reading the question carefully matters as much as the arithmetic.

Problem types in this test

  • Rates and work: distance = rate × time, average speed over a round trip, two pumps working together.
  • Ratios and percents: splitting a total in a ratio, successive discounts, mixtures and dilutions.
  • Algebra: one-variable equations and a pair of equations in two unknowns.
  • Geometry and data: circumference, angles, mean and median, probability without replacement.

Formulas you need are on the OAR formula sheet. To speed up the arithmetic itself, use theno-calculator math drill.

FAQ

What math is on the OAR?
The Math Skills Test covers arithmetic, fractions, percentages, ratios and proportions, basic algebra, geometry (area, perimeter, angles, circles) and data such as averages and probability, usually framed as word problems.
Can you use a calculator on the OAR math section?
No. Calculators are not allowed on any part of the OAR, so practice doing arithmetic, fractions and percentages by hand. The no-calculator math drill on this site is built for that.
How do I get faster at OAR word problems?
Learn the handful of setups that repeat (rate × time = distance, combined work rates, mixtures, percent change, ratios), write the equation before you calculate, and drill mental arithmetic so the calculation step is quick.

Sources

  1. Naval Aerospace Medical Institute. ASTB-E Frequently Asked Questions

Original practice questions from the OAR Prep question bank — not actual OAR or ASTB-E test items. The U.S. Navy does not endorse this test.

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