Question

Tony bowled 135 and 145 in his first two games. Write and solve a compound inequality to find the possible values for a third game that would give him and average between 120 and 130 inclusive.

Can someone please explain to me how to solve this? I've been stuck. :/

Answer 1

The average has to be at least 120 and at most 130
Average is calculated using the sum of all values divided by the number of values.
120 ≤ (135 + 145 + n)/3 ≤ 130
In inequalities we make what ever change we make on one side on both sides
360 ≤ 280 + n ≤ 390
80 ≤ n ≤ 110

Answer 2

120 ≤ (135 + 145 + n)/3 ≤ 130

360 ≤ 280 + n ≤ 390

80 ≤ n ≤ 110

120 ≤ (135 + 145 + n)/3 ≤ 130

80 ≤ n ≤ 110

So the last one, D