a. For each gender, construct a 90 % confidence interval for the population proportion who wash their hands in public restrooms.

Gibbs Baby Food Company wishes to compare the weight gain of infants using its brand versus its competitor's. A sample of 40 babies using the Gibbs products revealed a mean weight gain of 7.6 pounds in the first three months after birth. For the Gibbs brand, the population standard deviation of the sample is 2.3 pounds. A sample of 55 babies using the competitor's brand revealed a mean increase in weight of 8.1 pounds. The population standard deviation is 2.9 pounds.

1.

State the decision rule for 0.05 significance level : H0: μG ≥ μC ; H1: μG < μC. (Negative value should be indicated by a minus sign. Round your answer to 2 decimal places.)

  Reject H0 if z <

2.

Compute the value of the test statistic. (Negative value should be indicated by a minus sign. Round your answer to 2 decimal places.)

  Value of the test statistic

3.

Compute the p-value. (Round your answer to 4 decimal places.)

  p-value is

4.

Can we conclude that babies using the Gibbs brand gained less weight? Use the 0.05 significance level.