Question

a bank found that the average monthly checking balance of its customers is $10000 with a standard deviation of $4500. a random sample of 12 accounts is selected.

1. what is the probability that the average checking balance will be more than 13000

2. what is the probability that the monthly balance will be less than 4000

3.assume that this bank offers a special credit card to one percent of its customers with the highest checking balance. what is the minimum amount a customer should have to be eligible for that credit card?

Answer 1

Let account balance is normally distributed.

1:

2:

3:

Here we need to find x such that

P(X > x) = 0.01

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