Question

It is reported that software developers need an average of 10 months to develop a software.

Assuming that the time taken by software developer is normally distributed with a standard

deviation of 2.3 months. Given that the probability that a developer needs to develop a

software more than c months is 0.985. Find the value of c.

Answer 1

$P(Z>c)=0.985\to P(Z<c)=1-0.985=0.015.$

$c=-2.17.$

$\frac{x-10}{2.3}=-2.17.$

$x=10-2.3*2.17=5$ months.