A. for exercises 1 and 2, a set of data has a normal distribution with a mean of 120 and a standard deviation of 10.

1. find the interval about the mean within which 90% of the data lie.
a. 94.2-145.8
b. 103.5-136.5
c. 113.68-126.32
d. 100.4-139.6

2. find the probability that a value selected at random from this data is between 100 and 140.
a. 99.9%
b. 90%
c. 99%
d. 95.5%

b. in a random sample of 1000 exams, the average score was 500 points with a standard deviation of 80 points.

1. find the interval about the sample mean that has a 1% level of confidence.
a. 499-501
b. 479-520
c. 495-505
d. 493-507

2. find the interval about the sample mean such that the probability is 0.90 that the mean number lies within the interval.
a. 499-501
b. 495-505
c. 496-504
d. 368-632

3. find the probability that the mean score of the population will be less than five points from the mean score of the sample.
a. 95.5%
b. 38.3%
c. 98.8%
d. 62.5%

4. find the probability that the true mean is between 495 and 500.
a. 95%
b. 47.75%
c. 95.5%
d. 68.3%