Public Health and Nutrition
From the instant a fresh-baked chocolate-chip cookie is taken out of the oven, the time (in minutes) the wonderful aroma lasts has an exponential distribution with λ = 1/30. Suppose a chocolate-chip cookie is done baking and is taken out of the oven.
a. Find the mean, variance, and standard deviation for the time the aroma lasts.
b. What is the probability that the aroma lasts for at least 40 minutes?
c. What is the probability that the aroma lasts for between 30 and 50 minutes?
d. Find a value t such that the probability that the aroma lasts for at most t minutes is 0.90.
e. Suppose a second batch of cookies is taken out of the oven 10 minutes after the first. What is the probability that there will be no aroma from either batch 35 minutes after the first batch was done?