In the early months of some year once i added 0.5 million new accounts every day at this rate how many days would be needed to add 30 million new accounts

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)