Please help with this question

How do you find percent change? ? i will give brainliest for the bestme i don’t understand

The length of time for one individual to be erved at a cafeteria is a random variable having an ex- ponential distribution with a mean of 4 minutes. what is the probability that a person will be served in less than/3 minutes on at least 4 of the next 6 days?

The intensity, or loudness, of a sound can be measured in decibels (db), according to the equation 0b is the intensity of a given sound and lo is the threshold of hearing intensity. what is the intensity, in decibels, [l(db)], when 1 - 10"(%)? use a calculator. round to the nearest whole number a. 15. b. 32 c. 320 d. 737