Question

We measured the compressive strength for n = 16 specimens of concrete. Using the mean and standard deviation and assuming a normal population, we computed the following confidence interval [2271.7688, 2308.2312]. This interval is a confidence interval for the mean compressive strength at a level of confidence of 90%. We are told the the sample mean is x = 2290. What is the value of the sample standard deviation s?

Answer 1

ANSWER::

1)margin of error E=(2308.2312-2271.7688)/2

=18.2312

here for n-1=15 df and 90% CI , crtiical t =1.753

therefore sample standard deviation =E*sqrt(n)/t =18.2312*sqrt(16)/1.753

=41.6

(OR) TRY THIS

NOTE:: I HOPE YOUR HAPPY WITH MY ANSWER....***PLEASE SUPPORT ME WITH YOUR RATING...

***PLEASE GIVE ME "LIKE"...ITS VERY IMPORTANT FOR ME NOW....PLEASE SUPPORT ME ....THANK YOU