gibbs baby food company wishes to compare the weight gain of infants

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.