Question

A college student realized that he was spending too much money on music. For the remaining 5 months of the year his goal is to spend a mean of $⁢50 a month towards music. How much can he spend in December, taking into consideration that in the other 4 months he spent $20 , $⁢75 , $⁢20 , and $⁢90 , respectively? Round your answer to two decimal places, if necessary.

Answer 1

the expression for mean in this case is

$50 = \frac{1}{5}(d + 20 + 75 + 20 + 90) = \frac{1}{5}(d+205)$

with d standing for expenditure in December. Now solve for d:

$250 = d + 205\\d = 45$

The student has to spend $45 to meet his goal.