Herbert has sold 99, 37, 86, and 73 copeirs in the last 4 months, respectivly. How many copiers will he need to sell this month (s) to maintain an average of at least 75 sales per month.

Therefore 80 ceperies will he need to sell this month.

Step-by-step explanation:

Average: Average is the ratio of sum of all numbers to the total number present in the data.

Given that Herbert has sold 99, 37, 86 and 73 copeirs in the last 4 months.

Let he need to sell x copeirs in this month.

According to the problem,

⇒ 99+37+86+73+x= 75×5

⇒295 + x= 375

⇒x = 375 - 295

⇒ x= 80

Therefore 80 ceperies will he need to sell this month.