I got the first answer but I can not get b and c can someone help please:

Question:Tire pressure monitoring systems (TPMS) warn the driver when the tire pressure of the vehicle is 28% below the target pressure. Suppose the target tire pressure of a certain car is 28 psi (pounds per square inch.)

(a)At what psi will the TPMS trigger a warning for this car?(Round your answer to 2 decimal place.)

answer is: When the tire pressure isbelow 20.16 psi

(b)Suppose tire pressure is a normally distributed random variable with a standard deviation equal to 3 psi. If the car's average tire pressure is on target, what is the probability that the TPMS will trigger a warning?(Round your answer to 4 decimal places.)

Probability ____

(c)The manufacturer's recommended correct inflation range is 26 psi to 30 psi. Assume the tires' average psi is on target. If a tire on the car is inspected at random, what is the probability that the tire's inflation is within the recommended range?(Round your intermediate calculations andfinal answer to 4 decimal places.)

Probability ____