For the past 25 years, the average height of Americans has been 175 cm with a standard deviation of 10 cm. This year, a recent random sample of 100 Americans shows a mean height of 174 cm. At the 1% level of significance, you want to determine if Americans heights have now decreased. My conclusion is:

Question

anonymous · Answer

Just wanted to check my work..

My conclusion is to accept the null hypothesis..
reasoning to follow..

anonymous · Answer

H0:  u = 175  va Ha: u < 175 .. 
therefore a left tailed test.

samples: 100
StdDev = 10
Sample mean xbar = 175
Target mu             = 174
Std Err = 1
Z Data = 1
Alpha = 0.01  (level of significance)
Zcrit:    -2.326347 ...
P Value: 0.1587
Accept null hypothesis because P-Value > Alpha

anonymous · Answer

ah well, I think it's all wrong..

anonymous · Answer

computed z is -1, correct?

anonymous · Answer

$\mu = 175\text{, }\bar{x} = 174$

anonymous · Answer

everything else looks good.

anonymous · Answer

I had x bar and u_0 backwards.. in my equations..
now z data = -1

anonymous · Answer

thank you

anonymous · Answer

no worries!