Problem 81

Given information

Mean entry-level salaries for college graduates with mechanical engineering degrees and electrical engineering degrees are believed to be approximately the same. A recruiting office thinks that the mean mechanical engineering salary is actually lower than the mean electrical engineering salary. The recruiting office randomly surveys  entry-level mechanical engineers and  entry-level electrical engineers. Their mean salaries were  and  , respectively. Their standard deviations were  and , respectively.

Step-by-step explanation

Now, consider the following observations:

The null hypothesis is defined as follows:

The alternative hypothesis is stated as follows:

The difference between mechanical and electrical engineers means entry-level salary is .

   Student’s t (sample t-test, variances not pooled).

For the mean difference, the paired test static is,

After ENTER all of the values, look at the OUTPUT below.

Test statistic.  

The p-value from the output is .

Drawing a representation of the situation using the information from the last exercise.

The horizontal axis should be clearly labeled and scaled, and the region(s) matching the should be shaded on the graph.

   Decision: Null hypothesis is rejected.

   Conclusion: There is enough information to infer that the meantime for completing a lap in races differs from that in practices at the significance level.