n the paper "Persistent Pulmonary Hypertension of the Neonate and Asymmetric Growth Restriction" (

obstetrics & Gynecology

, Vol. 91, No. 3, pp. 336

-

341

, 2000

), M. Williams et

al. reported on a study of characteristics of neonates. Infants treated for pulmonary

hypertension, called the PH group, were compared with those not so treated, cal

led the

control group. One of the characteristics measured was head circumference. The mean

head circumference of the 10 infants in the PH group was 34.2 centimeters (cm).

Required:

a)

Assuming that head circumferences for infants treated for pulmonary hypertension

are normally distributed (symmetrical) with a population standard deviation of 2.1

cm. Determine a 90% confidence interval for the mean head circumference of all

such infants.

Provide a statement for your answer.

(5 marks)

b)

What are the two basic statistical assumptions to validate the confidence interval

result of part (a) above?

(2

m

arks)

c

)

Obtain the margin of error,

E

, for the confidence interval you found in part (a) above.

(

2

mark

s

)

d

)

Explain the meaning of

E

in this content in terms of the accuracy of the estimate.

(

2

mark

s

)

e

)

Determine the sample size required to have a margin of e

rror,

E

, of 0.5 cm with a

90% confidence level. Provide a statement.

(

4

marks)