0

It's a homework question. I am not looking for exact answer but need a direction. I have following question

H0: µ = 30
HA: µ != 30

We know that the sample standard deviation is 10 and the sample size is 70. For what sample mean would the p-value be equal to 0.05? Assume that all conditions necessary for inference are satisfied.

I am solving it as following

As our H0 is based on equal sign, so our test is two sided, we need to check both for small and larger values.
The P value of 0.05 in the probability table is equal to a z score of 1.65. We need to calculate S.E and then find mean using Z formula 

S.D = 10
n = 70
se <- S.D/sqrt(n)
# Z= (xbar- µ)/ S.E => xbar = Z * S.E + µ
xbar = (1.65*se)+30

So, in this way i get one mean value. but our test is two sided. so i need another mean value. I am not getting how can I solve it. Any suggestion or idea will be appreciable. Thanks

mc29
  • 85
  • 2
  • 10
  • 1
    You can do the same with -Z, can't you? Other than that, I believe for a two-sided test your Z = +- 1.96 and not 1.65. –  Nov 08 '17 at 08:48

0 Answers0