Acertain store found that last year the average (arithmetic mean) monthly sales from january through october was $120,000. in november and december, the monthly sales were 3 and 5 times, respectively, the average for the other 10 months. what was the store’s average monthly sales last year?

$180,000

Explanation:

Given:

Mean salary from January through October = $120,000

Salary for November = 3 times the mean salary = 3 × $120,000

= $360,000

Salary for December = 5 times the mean salary = 5 × $120,000

= $600,000

Also,

the total salary for the rest 10 months = 10 × Mean salary

or

the total salary for the rest 10 months = 10 × $120,000 = $1,200,000

therefore,

the total salary = $360,000 + $600,000 + $1,200,000 = $2,160,000

Hence,

the average salary for each month =

or

the average salary for each month = $180,000

i have economics during second block which is easy to me. anyways, i think b.