NARRBEGIN: Starting Salary
Starting Salary
in Testing the Hypotheses $H _ { 0 } : \mu _ { 1 } - \mu _ { 2 } = 0$

NARRBEGIN: Starting Salary
Starting Salary
In testing the hypotheses $H _ { 0 } : \mu _ { 1 } - \mu _ { 2 } = 0$ vs. $H _ { 1 } : \mu _ { 1 } - \mu _ { 2 } \neq 0$ , two random samples from two populations of college of business graduates majoring in global marketing and international business produced the following statistics regarding their starting salaries (in $1000s): $n _ { 1 } = 50$ , $\bar { x } _ { 1 } = 35$ , $s _ { 1 } = 28$ , $n _ { 2 } = 50$ , $\bar { x } _ { 2 } = 30$ , and $s _ { 2 } = 10$ . (Assume the salaries have normal distributions.)
NARREND
-The service manager of a car dealer wants to determine if owners of new cars (two years old or less) tune up their cars more frequently than owners of older cars (more than two years old). From his records he takes a random sample of ten new cars and ten older cars and determines the number of times the cars were tuned up in the last 12 months. The data follow. Do these data allow the service station owner to infer at the 10% significance level that new car owners tune up their cars more frequently than older car owners?
$$\begin{array}{l}\text { Frequency of Tunsups in past 12 Month }\\\begin{array} { |c | c| } \hline \text { New Car Owmers } & \text { Old Cars Owners } \\\hline 6 & 4 \\3 & 2 \\3 & 1 \\3 & 2 \\4 & 3 \\3 & 2 \\6 & 2 \\5 & 3 \\5 & 2 \\4 & 1 \\\hline\end{array}\end{array}$$