Suppose you wanted to estimate the proportion of adults who write with their left hands and decide to watch a sample of n people signing credit card receipts at a mall.

a. Do you think this sample would be representative for the question of interest? Explain.

b. Assuming that the sample was representative, how many people would you have to include to estimate the proportion with a margin of error of 5%?

c. Suppose you observed 500 people and 60 of them signed with their left hand. What interval of values would you give as being likely to contain the true proportion of people in the larger population who would sign with their left hand?

d. Is the sampling plan that was used a probability sampling plan? Explain.