Answer:
0.1007
Step-by-step explanation:
Given :
Average gain, μ = 0.8
Standard deviation, σ = 0.7
Number of companies, n = 20
Obtaining the standardized value ;
Zscore = (x - mean) / (σ/√n)
Zscore = (1 - 0.8) / (0.7/√20)
Zscore = (0.2 / 0.1565247)
Z = 1.27775
Using the Z probability calculator :
P(Z > 1.27775) = 0.10067
P(Z > 1.27775) = 0.1007 ( Z probability calculator)