The ratio of football cards to baseball cards is 3:2 and the ratio of baseball cards to basketball cards is 3:1. To solve this problem, we need the baseball card side of each ratio to be equal so we need to rewrite the ratios in terms of a common number of baseball cards. (Think of this like finding the common denominator when adding fractions.) The ratio of football to baseball cards can also be written as 9:6 and the ratio of baseball cards to basketball cards as 6:2. So, the ratio of football cards to basketball cards is football:baseball, baseball:basketball or 9:6, 6:2 which reduces to 9:2.

To find the average of these 4 numbers add them together then divide by 4:

\( \frac{17 + 9 + 16 + 10}{4} \) = \( \frac{52}{4} \) = 13

Average speed in miles per hour is the number of miles traveled divided by the number of hours:

Solving for time:

time = \( \frac{\text{distance}}{\text{speed}} \)
time = \( \frac{275mi}{55mph} \)
5 hours

In order to find how many additional workers are needed to staff the extra crews you first need to calculate how many workers are on a crew. There are 10 workers at the company now and that's enough to staff 5 crews so there are \( \frac{10}{5} \) = 2 workers on a crew. 10 crews are needed for the busy season which, at 2 workers per crew, means that the roofing company will need 10 x 2 = 20 total workers to staff the crews during the busy season. The company already employs 10 workers so they need to add 20 - 10 = 10 new staff for the busy season.

To raise a term with an exponent to another exponent, retain the base and multiply the exponents: