4. A study was conducted to determine the average weight of newborn babies. The distribution of the weight of

newborn babies has a population standard deviation of = 1.25lbs. A random sample of 100 newborn babies

was taken and weights measured. The mean weight of the babies in the sample was 7.3 lbs.

a. Construct a 95% confidence interval for the true mean weight of newborn babies.

i. (7.055 , 7.545)

ii. (7.052 , 7.548 )

iii. (7.245 , 7.355 )

iv. (6 , 8.6 )

b. Interpret the confidence interval in a.

i. There is a 95% probability that is in the interval.

ii. We are 95% confident that the is captured in the interval.

iii. All of the above.

c. Write the null and alternative hypotheses to determine if the true mean weight of newborn babies is

less than 7.75 lbs.

i. H0: = 7.3

HA: < 7.3

ii. H0: = 7.75

HA: < 7.75

d. Conduct a statistical test to determine if the true mean weight of newborn babies is less than 7.75 lbs.

Use = 0.02.

i. Pvalue

1. 0.000159

2. 0.00345

3. 0.2617

4. 0.9998

ii. Conclusion

1. There is enough evidence to conclude that the true mean weight of newborn babies is

less than 7.75 lbs.

2. There is NOT enough evidence to conclude that the true mean weight of newborn

babies is less than 7.75 lbs.

3. There is enough evidence to conclude that the true mean weight of newborn babies is

equal to 7.75 lbs.