Question

Helen practiced the piano 5 days last week. The list below shows the number of minutes she practiced each day: 20,25,30,20,30 What is the MAD (mean absolute deviation) in Helen's practice times?

Answer 1

4

Explanation:

Given the data:

X : 20,25,30,20,30

Mean absolute deviation :

Σ(x - xbar) / n

n = sample size = 5

xbar = ΣX / n = (20+25+30+20+30) /5

xbar = 25

((20-25) + (25-25) + (30-25) + (20-25) + (30-25)) / 5

We take the absolute values, hence, negative signs are ignored :

(5 + 0 + 5 + 5 + 5) / 5

20 / 5

= 4