Question

Brian recorded the amount of money he spent over the last 5 days. He knows that the average amount of money he spent was $25.72. On four of the Five days, Brian spent $15.50, $28.41, $31.02, and $10.66. Determine how much Brian spent on the fifth day.

Answer 1

Hello! In order to figure out how much Brian spent on the fifth day, we need to use the average amount ($25.72) and the totals from the other four days.

An average is calculated by adding up all individual units (in this case the 5 daily values) and then dividing by the total number of units (in this case, 5). For now, let's call the amount that Brian spent on day 5, “x”. If we do that, we can set up our formula like this:

Average = (Day 1 + Day 2 + Day 3 + Day 4 + Day 5)/5

$25.72 = (15.50 + 28.41 + 31.02 + 10.66 + x)/5

Simplifying this equation, we get:

25.72 = (89.59 + x)/5

Multiply both sides by 5:

$128.60 = $85.59 + x

$43.01 = x

Therefore, on the fifth day, Brian spent $43.01.

Hope that helps!