Help on AP Statistics Sampling Distributions !!! Need Explanations!! (Photo Provided)

1. A dealer states that 90% of all automobiles sold have air-conditioning. If the dealer sells 250 cars, find the probability that less than 220 will have air-conditioning.

2. The average April electric bill in a certain area is $72 with a standard deviation of $6. The amount of the electric bills are normally distributed. Find the probability that the mean of the bills for 15 randomly selected the residents will be more than $75.

3. Purchases at the Train Station Hobby shop are normally distributed with a mean of $12.50 and standard deviation of $2.50. Find the Probability that the mean of a random sample of 40 purchases is between $12.50 and $13.00

4. In a corporation, 30% of the employees choose to enroll in a financial investment program offered by the company. Find the probability that of 800 randomly selected employees at least 28% have enrolled in the program.

5. The lifetime of a particular brand of toasters are normally distributed with an average lifetime of 14 months, with a standard deviation of 4 months. If 20 toasters are selected at random, find the probability that the mean lifetime of the sample will be less than 1 year.