Question

Assume that the correct degrees of freedom are 10. What is the critical cutoff value for the test in part (a)

1. Using symbols, state the null and alternative hypotheses to test for evidence of a difference in the mean number of hours the battery pack models will function before needing to be recharges.
   1. H0:mu1-mu2=0
      Ha: mu1-mu2 not equal 0

   2. n1=9, sample mean = 5 and SD = 1.2

      n2=7, sample mean = 6.5 and SD = 1.7

Answer 1

Solution:

From part a, we are given that the hypothesis test is two tailed because alternative hypothesis is of ‘not equal to’ type.

Level of significance is not given. So, we assume default level of significance as 5% or α = 0.05.

We are given correct degrees of freedom as df = 10.

Now, we have to find critical cut-off values for two sample t test for population means by using t-table.

So, required critical value for two tailed test, df = 10, and α = 0.05 is given as below:

Critical values = -2.3060 and 2.3060

(By using t-table)