ASVAB Mathematics Knowledge Practice: Circles

By Consumer Dummies

If you love circles—and who doesn’t!—then you’re in for a treat when you take the Mathematics Knowledge subtest on the ASVAB. Of course, enthusiasm isn’t enough; you should also know the formulas for the circumference and area of a circle, and also how to switch a formula around to get the right answer.

Practice questions

  1. Based on this diagram,

    asvab-radius

    find the circle’s radius.

    ASVAB_1901

  2. Based on this diagram,

    asvab-circumference

    find the circumference of the circle.

    ASVAB_1902

Answers and explanations

  1. The correct answer is Choice (B).

    The formula for the area of a circle is

    ASVAB_1903

    so create your own equation using the information you already have:

    ASVAB_1904

  2. The correct answer is Choice (C).

    First, notice that the answer choices are in terms of pi. That means you won’t have to multiply by 3.14.

    The formula to find the circumference of a circle is

    ASVAB_1905

    Because you know the diameter is 210 feet, the radius is 105 feet. Use what you know in the formula:

    ASVAB_1906

    You can solve the problem more quickly using an alternate formula for the circumference,

    ASVAB_1907

    where d is the diameter. Mentally insert d = 210 in for d, and you get

    ASVAB_1908