Question

HI PLS HELP!!! A student scored 83 and 91 on their first two quizzes. Write and solve a compound inequality to find the possible values for a third quiz score that would give them an average between 85 and 90, inclusive.

Answer 1

(Not my answer, stolen)

Answer 2

between 81 and 96 inclusive

Explanation:

well the average of 3 scores is

something / 3

so we have

`85\leq (83+91+x)/(3)\leq 90`

now solving it

`85(3)\leq 174+x\leq90(3)\\\\255\leq 174+x\leq 270\\\\81\leq x \leq 96`