If x is the average (arithmetic mean) of m and 9, y is the average of 2m and 15, and z is the average of 3m and 18, what is the average of x, y, and z in terms of m?

A) m+6

B) m +7

C) 2m+14

D) 3m+21

The average of three numbers is 42. The first two numbers differ by 1 and the average second and third number is 47. What are the three numbers

1. If is the cost of producing x units of a commodity, then the average cost per unit is . Show that if the average cost is a minimum, then the marginal cost equals the average cost.

2. If in dollars, find (i) the cost, average cost, and marginal cost at a production level of 1000 units; (ii) the production level that will minimize the average cost; and (iii) the minimum average cost.

what is the average of 22.10; 13.45; 25.10; 17.20; 19.10?