Question

11. The average age of 19 students is 20 years. If the teacher is added the

average age increases by 2. How old is the teacher?
b. 80
a. 60
c. 38
d. 22

Answer 1

a

Explanation:

average is calculated as

average =
`(sum)/(count)`

then

`(sum)/(19)` = 20 (multiply both sides by 19 )

sum = 380

let the teachers age be then adding the teacher

`(380+x)/(20)` = 22 ( multiply both sides by 20 )

380 + x = 440 ( subtract 380 from both sides )

x = 60

the teacher is 60 years old