Question

jackie scored 82 and 88 on her first two quizzes. Write and solve a compound inquality to find the possible values for a third quiz score that would give her an average between 80 and 85, inclusive.

Answer 1

80 <= (82+88+x)/3 <= 85  this is the compound inequality

multiply all sides by 3

240 <= (82+88+x) <= 255

combine like terms

240 <= (170+x )<= 255

subtract 170 from all sides

70 <= x<= 85

She must score between 70 and 85 inclusive