8.69 Work agreement for nannies According to a 2016 poll of families in New York City who employ a nanny, 75%

did not enter into a written work agreement with them.

a. What has to be assumed about this sample to construct a confidence interval for the population proportion of all families who did not enter into a written work agreement with their nannies?

b. Assuming the size of the sample in this poll is 5000, construct a 99% confidence interval for the population proportion.

c. Can you conclude that more than 70% of families who employ nannies do not enter into a written work agreement with them?