Pre Algebra: Creating Ratios

1. Seven of a 15 member marching band are girls and the remainder are boys. What is the ratio of boys to girls in the marching band?

ANSWER: (D) 8:7

If you have 15 members and 7 are girls, that means that the remaining 8 must be boys. If there are 8 boys and 7 girls then the ratio of boys to girls is 8:7.

2. An hour long TV program has 18 minutes of commercials. What is the ratio of commercial time to the total air time?

ANSWER: (A) $\dfrac{3}{10}$

An hour long TV program lasts 60 minutes. If 18 minutes of the program is commercials then the ratio of commercials to total air time is 18/60, which can be simplified to 3/10. (18 divided by 6= 3 and 60 divided by 6= 10)

3. Richie is learning how to multiply fractions. On his last homework assignment, he got 8 questions correct and 9 questions incorrect. What is the ratio of questions he got incorrect to the total number of questions on the assignment?

ANSWER: $\dfrac{9}{17}$

Since Richie got 8 correct and 9 incorrect, we know that there are 17 questions total. (8+9=17) Thus, the ratio of incorrect to the total questions is 9 to 17.