Statistics and Probability Answers

Mean: 81
Median: 83
Mode: 80
Standrard Deviation: 9
First Quartile: 60
3rd Quartile: 89
90th precentile: 95

1. What score did half of the students exceed?
2. About what percent of the students' grades exceeded 89?

3. About what percent of students' grades were less than 95?

4. If there were 100 students enrolled in the class what would be the total of all the scores?

5.What test score represents one standard deviation above the mean?

6. What test score represents 1.5 standard deviations below the mean?

explain the rolling of a fair die and then flipping of a fair coin with the help of tree diagram

Which of the following is an example of inverse correlation?
a. Weight and height
b. Level of test anxiety and grade (A, B, and C)
c. The amount of exercise and height
d. The amount of exercise and level of depression

weighted average question. people taking courses. I have the following:
% of people and #of people and their completion rate.
20% = 6 people = 72% completion rate of courses
30% = 9 people = 85% completion rate of courses
50% = 15 people = 95% completion rate
I know it is wrong to take the average of 72%, 85% 95% to get the average completion rate ...but how do i figure out the weighted average?

A Harris Interactive national telephone poll in 2002 asked, "Do you think adults should be allowed to legally use marijuana for medical purposes, if their doctor prescribes it, or do you think that marijuana should remain illegal even for medical purposes." The results showed that 80 percent of respondents answered, "Yes, it should be legal for medical purposes." Assuming that this accurately reflects national attitudes, find the probability when eight Americans are chosen at random:
a. Exactly three said "Yes."
b. Six or fewer said "Yes."

the letters m,i,s,s,i,s,s,s,p,p,i,r,i,v,e,r are written on cards and placed face down. what is the probability that a random selection of one card will be an s?

40% of couples who plan to get married this year are planning destination weddings. In a random sample of 12 couples who plan to marry, find the probability that
a) exactly 6 couples will have a destination wedding
b) at least 2 couples will have a destination wedding
c) fewer than 3 couples will have a destination wedding

kp cafeteria coffee is very popular. on average it sold 10 cups of coffee per hour. find the probability that exactly 12cups of coffee were sold in 2 hours.

The fuel consumption of a Boeing747 in cruising mode averages 3213 gallons per hour. Assume that the consumption is normally distributed with a standard deviation of 180 gallons per hour. If a 747 is in cruising mode, what is the probability the fuel consumption is
(a) between 3000 and 3500 gallons per hour?
(b) less than 3000 gallons per hour?
(c) more than 3500 gallons per hour?
(d) What does this information tell you about the fuel consumption of a 747?

In a group of 15 boys, there are 6 scouts. In how many ways can 8 boys be selected, so as to include

(i) exactly 3 scouts

(ii) at least 3 scouts

(iii) at the most 3 scouts