Question

Chang is participating in a 4-day cross-country biking challenge. He biked for 70, 63, and 66 miles on the first three days. How many miles does he need to bike on the last day so that his average (mean) is

65miles per day?

Answer 1

(70 + 63 + 66 + x) / 4 = 65
(199 + x) / 4 = 65
199 + x = 65 * 4
199 + x = 260
x = 260 - 199
x = 61 <== he would need a 61