Question

A student scores marks of 66 and 72 on two tests. What is the lowest mark she can obtain on a third test to have an average for the three tests greater than or equal to 75?

Answer 1

Answer:

let x=lowest mark on the third test

(66+72+x)/3≥75

132+x≥225

x≥225-132

x≥93

Answer 2

Answer:

87

Step-by-step explanation:

66+72+x/3 greater than or equal - 75

138+x greater than or equal - 225 (multiply both sides x3)

x greater than or equal - 87    (225-138)

lowest mark obtainable to achieve average greater than or equal to 75

= 87