What do you need help with? What have you tried? What method are you supposed to be using?
A population of light bulbs has average lifetime of 600 hours and a standard deviation of 100 hours. Assume the population follows a normal distribution.
A) If you bought a four-pack of bulbs from this population, what is the probability that the average lifetime for the four bulbs is less than 500? Consider the four pack to be sample of n=4.
B) Suppose you bought a 16-paco of bulbs from this population. What is the probability that the average lifetime for the 16 bulbs is less than 500 hours? Consider the 16-pack to be your sample of n=16.