Health care workers who use latex gloves with glove powder on a daily basis are particularly susceptible to developing a latex allergy. Symptoms of a latex allergy include conjunctivitis, hand eczema, nasal congestion, skin rash, and shortness of breath. Each in a sample of 46 hospital employees who were diagnosed with latex allergy based on a skin prick test reported on their exposure to latex gloves (Current Allergy & Clinical Immunology, Mar. 2004). Summary statistics for the number of latex gloves used per week are  = 19.3, s = 11.9.
a. Give a point estimate for the average number of latex gloves used per week by all health care workers with a latex allergy.
b. Form a 95% confidence interval for the average number of latex gloves used per week by all health care workers with a latex allergy.
c. Give a practical interpretation of the interval, part b.
d. Give the conditions required for the interval, part b, to be valid.