Tried to solve it but it was wrong

Question

Medical research has shown that repeated wrist extensions beyond 20 degrees increase the risk of wrist and hand injuries. Each of 24 students at a university used a proposed new computer mouse design, and while using the mouse, each student's wrist extension was recorded. Data consistent with summary values given in a paper are given here.

26 28 23 25 27 25 25 24 24 24 25 28 22 25 24 28 27 26 31 25 28 27 27 25

Use these data to estimate the mean wrist extension for people using this new mouse design using a 90% confidence interval. (Round your answers to three decimal places.)

Answer 1

sample mean = arithmetic average = sum/n= xbar = 25 19/24

= about 25.7917

-about25.792

calculate standard deviation= s

some calculators will calculate s for you

two tails, n=24, use t tables, alpha =.10, degrees of freedom=

confidence interval = xbar +/- ts/sqrn