00:01
Here, given that h0, mu is equal to 12 versus h1, mu is greater than 12, and n is given us 64, and sample mean x bar is equal to 11 .5, and sample standard deviation s is equal to 2 .5.
00:29
For a part we have to find standard error which is equal to s by square root of n, which is equal to 2 .5 divided by square root of 64, which is equal to 0 .3125.
00:52
This is the required standard error.
00:58
For b part, we have degrees of freedom is equal to n minus 1, which is equal to 64 minus 1, which is equal to 63.
01:12
And confidence level 1 minus alpha is equal to 90 percentage.
01:19
The critical value t star is equal to 1 .6694.
01:30
This is the critical value and the confidence interval is equal to mu plus or minus sorry x bar plus or minus t into standard error which is equal to 11 .5 plus or minus 1 .6694 into standard error is equal to 11 .5 plus or minus 1 .6694 into standard error is 0 .3125 which is equal to 10 .9783 .12...