4. A company pays its employees an average wage of $16.00 an hour with a standard deviation of $ 2.00. If the wages are approximately normally distributed, determine:

a) The probability that a worker is getting a wage between $15.00 and $16.50 an hour

b) The minimum wage of the highest 10% of the wages

c) If 36 employees are selected, what is the probability that the mean of their wages is greater than $15.50 an hour?