Four observations 5, 7, 11 and x have an arithmetic mean of 8 and variance 5

MATHEMATICS · Single correct · A Level · Mathematics · Data presentation and interpretation · Data presentation and interpretation

Problem

Four observations 5, 7, 11 and x have an arithmetic mean of 8 and variance 5. Find the value of x. (a) 6 (b) 13 (c) 9 (d) 8