Statistics and Proportions

In a list of numbers, if a particular number appears most frequently, what is it called?

• Mode

• Average

• Median

• Mean

What is the mean of the numbers 5, 8, 12, 15, and 20?

• 25

• 10

• 18

• 12

Find the median of the following set of numbers: 10, 15, 20, 25, 30.

• 18

• 22

• 28

• 20

Calculate the range of the numbers 3, 7, 12, 18, 25.

• 22

• 15

• 20

• 30

If the ratio of pencils to pens in a box is 7:5, how many pens are there if there are 21 pencils?

• 15

• 18

• 12

• 14

Answer explanation

To find the number of pens, set up fractions as an equality like this: 7/5 =21/x. 7*3 is 21, so multiply the 5 by 3 as well to get the number of pens, 15.

If the ratio of boys to girls in a class is 5:6 and there are 30 girls, how many boys are there?

• 25

• 20

• 24

• 28

If the ratio of red balls to blue balls in a bag is 5:3, how many blue balls are there if there are 20 red balls?

• 12

• 15

• 8

• 10

Answer explanation

If the ratio of red balls to blue balls is 5:3, and there are 20 red balls, set up an equality like this: 5/3 = 20/x. To get from 5 in the left numerator to 20 in the right numerator, multiply 5*4. Since the numerator is multiplied by 4, the denominator would also be multiplied by 4. 3*4 = 12.

If a recipe calls for a ratio of 2 cups of flour to 3 cups of sugar, how many cups of sugar are needed if 8 cups of flour are used?

• 6

• 10

• 12

• 14

If the ratio of cats to dogs in a pet store is 3:4, how many cats are there if there are 12 dogs?

• 9

• 16

• 8

• 10

Answer explanation

To find the number of cats, use the ratio 3:4. Since there are 12 dogs, divide 12 by the 4 in the ratio, since that is the number that represents dogs. When you divide 12 by 4, you get 3, telling you to multiply the 3 in the ratio, representing the cats, by 3. Therefore, there are 9 cats.

If the ratio of cats to dogs is 3:4, how many cats are there if there are 20 dogs?

• 15 cats

• 25 cats

• 30 cats

• 10 cats