Question 2

Each day, John's mother gives him money before he goes to school: 50% of the time he gets $5, 35% of the time he

gets $10 and the rest of the time he gets $20.

1. Determine the expectation and variance for how much money John gets each day.

2. For the next 100 school days, John plans to save all the money his mother gives him. What is the approximate

probability he is able to save more than $1000? Assume independence.

3. If he realizes he has to spend an average of $4 a day with a standard deviation of $0.75, what is the approximate

probability that he saves less than $400? Assume independence.