Statistics One Sample Left tail test t-test

Question
It is claimed that a large corporation discriminates against its women employees in its promotion practices. Over many years, the meantime before first promotion for its male employees has been 3 years. A random sampleof 20 females who had worked there many years showed a mean time of 3.8 years before its first promotion, with s=1.2 years. Using level of significance of 5% see of the datasupports the claim.

Null Hypothesis :
H0 : µ = 3 years and that there is no discrimination against women …

The solution to the one-tail hypothesis test problem is given in step by step procedure with all the working and explanation so that the student could understand easily and use this solution as a model solution to solve other similar type of problems. A single sample hypothesis test with a hypothesized value of mean is used.