Question

1. In a population of heroin users, the mean duration of heroin abuse is 5 years with a standard deviation of 3 years. If you randomly sample 81 heroin users from this population, what is the probability that your sample of 81 will yield a sample mean duration of heroin abuse between 4 and 6 years?

2. The mean length at birth of 24 male infants was 53 cm with a standard deviation of 9.6 cm. Assuming normality, calculate a 98% confidence interval for true mean lengths of male newborns.

n=____ Ῡ= _____ s=______

98% CI for μ is (__________, __________)

3. Mother’s attitudes toward labor and delivery were studied on two groups of new mothers:

Group 1 attended prenatal classes

Group 2 did not attend prenatal classes

Group              n          Ῡsample mean             s

1                      15        4.75                             1

2                      17        3.0                               1.5

Do the data suggest that attendees on average score higher than non-attendees. Test at alpha =.05 using the pooled procedure. {hint s_p²=1.667}

1 H₀:__________   H_a:_____________                        5.Decision: {Circle one} Reject H₀ or Fail to Reject H₀

2 α=_________                                                               6. P-value _____________________________

3 Critical Value   _________                                         7.Statement:___________________________________

                                                                                                               ___________________________________

4Test stat ___________

                                            

Answer 1

( 2 )

n = 24 , y bar = 53 , s = 9.6

let y bar = x bar

98% CI for μ is ( 48.10 , 57.90 )