Solve the following:
Q1. The number of hours needed by students in an economics course to complete a term paper are as follow:
|
Hours
|
# of students (frequency)
|
|
4
|
15
|
|
5
|
11
|
|
6
|
19
|
|
7
|
6
|
|
8
|
9
|
|
9
|
16
|
|
10+
|
2
|
A student is selected at random. Find the following probabilities.
a. the student took more than 9 hours
b. the student took less than 6 hours
c. the student took between 7 and 9 hours, inclusive.
Q2. A box holds 5 blue chips, 14 orange chips, and 6 yellow chips. If a chip is randomly selected, what is the probability that it is yellow?
Q3. A company makes batteries in batches of 20, with a 3% rate of defects. Find the mean and standard deviation for the random variable x, the number of defects per batch.
Q4. Find the mean and standard deviation for the random variable x, given the following distribution:
|
x
|
1
|
2
|
3
|
4
|
5
|
6
|
|
P(X=x)
|
0.15
|
0.15
|
0.13
|
0.12
|
0.10
|
0.35
|
Q5. The variable x is normally distributed. The mean is 15.2, and the standard deviation is 0.9. if an item is randomly selected, find the probability that it is greater than 16.1.