The average (arithmetic mean) of four numbers is 4a + 16. when a fifth number is added, the average becomes 5a + 20. the fifth number is

a. a - 4
b. a + 4
c. 4a + 4
d. 4a + 16
e. 9a + 36

Step-by-step explanation:

The average (arithmetic mean) of four numbers is 4a + 16. When a fifth number is added, the average becomes 5a + 20.

The average (arithmetic mean) of four numbers is 4a + 16.

Sum of 4 numbers = 4 times the average

Sum of 4 numbers =

sum  of 5 numbers = 5 times the average of 5 numbers

Sum of 5 numbers =

fifth number = sum of 5 numbers minus the sum of 4 numbers

15

step-by-step explanation:

we are given the following expression and we are to solve it and find the product:

-13 × (-5)

solving the given expression in the standard order of solving a mathematical expression, beginning with the opening of brackets and then multiplying the terms and changing their signs.

-3 × -5 = 15 (answer is positive because when negative is multiplied with negative, it gives a positive answer)