Question

* Make sure you turn in your code (take a screen shot of your code in R)and answers. Conduct the hypothesis
and solve questions by using R.
2) A random sample of 12 graduates of a secretarial school averaged 73.2 words per minute
with a standard deviation of 7.9 words per minute on a typing test. What can we conclude,
at the .05 level, regarding the claim that secretaries at this school average less than 75
words per minute on the typing test? (You may treat the number of words that a secretary
types in one minute as being normally distributed.)

Answer 1

Given,

Our hypothesis is,

(Left tail test)

Test statistics:

In R,

Lets create a function to calculate test statistics:

ttest<-function(xbar,mu,s,n){

a<-xbar-mu

b<-s/sqrt(n)

statistics<-a/b

return(statistics)

}

ttest(xbar=73.2,mu=75,s=7.9,n=12) ### this will give

absolute value of t is 0.789289

Degree of freedom = n-1 = 12-1 = 11

(Given)

Critical t value at 0.05 significance level for 11 degree of freedom for one tail test is calculated in R as:

qt(1-0.05,11)

1.795885

Since, , is fail to reject

Conclusion: Therefore, we conclude that there is not enough evidence to support the claim that secretaries at the school average less than 75 words per minute on the typing test.