PLEASE, USE A T or Z or BINOMIAL TABLE DISTRIBUTION WHEN APPROPRIATE. I COULD NOT UPLOAD THE ONES I RECEIVED FROM CLASS.

QUESTION 1

A bank has kept records of the checking balances of its customers and determined that the average daily balance of its customers is $300 with a standard deviation of $48. A random sample of 144 checking accounts is selected.

1. What is the probability that the sample mean will be more than $306.60?
2. What is the probability that the sample mean will be less than $308?
3. What is the probability that the sample mean will be between $302 and $308?
4. What is the probability that the sample mean will be at least $296?

QUESTION 2

Nobel Dylan hasdetermined that 25% of all its MP3-songs sales are credit sales. A random sample of 75 sales is selected.

1. What is the probability that the sample proportion will be greater than 0.34?
2. What is the probability that the sample proportion will be between 0.196 and 0.354?
3. What is the probability that the sample proportion will be less than 0.25?
4. What is the probability that the sample proportion will be less than 0.10?

QUESTION 3

An infinite population has a mean of73 and a standard deviation of43. A sample of size 121 is taken at random from this population. The standard error of the sample mean equals:

QUESTION 4

As the sample size becomes larger, the sampling distribution of the sample mean approaches a

Poisson distribution ? hypergeometric distribution? binomial distribution ? Normal Distribution?

QUESTION 5

If all possible samples of sizenare drawn from an infinite population with a mean of 40 and a standard deviation of21, then the standard error of the sample mean equals 2 for samples of size:

QUESTION 6

If two random samples of sizes 30 and 36 are selected independently from two populations with means 78 and 85, and standard deviations 12 and 15, respectively, then the mean of the differenceis equal to:

7

78/30 85/36 = 0.24

7

(78 85) / (30 36) = 1.17

QUESTION 7

If two random samples of sizes 30 and 36 are selected independently from two populations with means 78 and 85, and standard deviations 12 and 15, respectively, then the standard error of the differenceandis equal to:

0.833

0.904

3.324

3.391