ANSWER THE FOLLOWING:

Solve the following and sketch the graph of the entire given problem.

1. If scores are normally distributed with a mean of 80 and a standard deviation of 10, what percent of the scores is:

a. equal or greater than 90?

b. equal or less than 60?

c. from 75 to 100?

d. find the number of students whose score is at least 75 if there are 1,000 students in the class.

2. There are 520 graduating students at a certain college who were given an IQ tests. Assuming that their IQs are normally distributed with a mean of 250 and a standard deviation of 18, how many graduating students have an IQ of:

a. 150 and lower?

b. 240 and higher?

c. 300 to 450?

d. 200 to 300?

3. A normally distributed data has a mean of 100 and a standard deviation of 8.

a. What is the lowest value that belongs to the upper 15% of the distribution?

b. What are the two extreme scores, outside of which only 5% of the distribution are expected to fall?

c. In what range does the middle 90% of all scores lie?

d. What are the values that belongs to the lower 10% of the distribution?

4. In the final examination in NCP 2104, the mean grade was 75 and the standard deviation was 6. In NCP 2105, the mean grade was 80 and the standard deviation was 8. Ralph scored 77 in NCP 2104 and 84 in NCP 2105.

a. In which subject was his standing higher?

b. What percentage that Ralph surpasses his classmates in NCP 2104 and NCP 2105?

c. What is Ralph's percentile rank in each of the subjects?