1. Estimate the indicated probability by using the normal distribution as an app
ID: 3126859 • Letter: 1
Question
1. Estimate the indicated probability by using the normal distribution as an approximation to the binomial distribution. With n = 20 and p = 0.60, estimate P(x < 8).
0.4953
0.0202
0.0668
0.4332
2
A library determines that its books are returned on time 90% of the time. If 450 books are checked out, what is the probability that more than 410 will be returned on time?
.2852
.7852
.1949
.2420
3
A car rental has cars with an average of 9000 miles and standard deviation of 1200. If 25 cars are in a lot, what is the probability there average miles will be less than 9500 miles?
.4812
.0188
.9812
.3372
4
Use the normal distribution to approximate the desired probability. International Airlines reports that 74% of its planes are on time. A check of 60 randomly selected planes shows that 38 of them arrived on time. Find the probability that among the 60 planes, 38 or fewer arrive on time.
.9591
.0409
.0316
.4591
5
Estimate the indicated probability by using the normal distribution as an approximation to the binomial distribution.
The probability that a radish seed will germinate is 0.7. Estimate the probability that of 140 randomly selected seeds, exactly 100 will germinate.
0.0679
0.0669
0.0769
0.9331
6
Use the normal distribution to approximate the desired probability. Find the probability of getting at least 30 fives in 200 tosses of a fair 6-sided die.
.6229
.8871
.5871
.7673
7
For the binomial distribution with the given values for n and p, state whether or not it is suitable to use the normal distribution as an approximation. n = 31 and p = .9
Normal approximation is not suitable.
Normal approximation is suitable.
8
Use the normal distribution to approximate the desired probability. Find the probability of getting at most 30 fives in 200 tosses of a fair 6-sided die.
.2946
.3229
.1871
.4936
9
For the binomial distribution with the given values for n and p, state whether or not it is suitable to use the normal distribution as an approximation. n = 54 and p = .7
Normal approximation is not suitable.
Normal approximation is suitable.
10
In one region, the September energy consumption levels for single-family homes are found to be normally distributed with a mean of 1,050 kWh and a standard deviation of 218 kWh. If 50 different homes are randomly selected, find the probability that their mean energy consumption level for September is greater than 1,075 kWh.
0.2090
0.2910
0.4562
0.0438
11
A library determines that its books are returned on time 90% of the time. If 450 books are checked out, what is the probability that more than 400 will be returned on time?
.2852
.7852
.2148
.7611
12
Suppose that replacement times for washing machines are normally distributed with a mean of 9.3 years and a standard deviation of 1.1 years. Find the probability that 70 randomly selected washing machines will have a mean replacement time of less than 9.1 years.
0.4357
0.4286
0.0714
0.0643
13
For the binomial distribution with the given values for n and p, state whether or not it is suitable to use the normal distribution as an approximation. n = 18 and p = .2
Normal approximation is not suitable.
Normal approximation is suitable.
14
Suppose that replacement times for washing machines are normally distributed with a mean of 9.3 years and a standard deviation of 1.1 years. Find the probability that 70 randomly selected washing machines will have a mean replacement time less than 9.1 years.
0.0643
0.4357
0.4286
0.0714
15
A car rental has cars with an average of 9000 miles and standard deviation of 1200. If 25 cars are in a lot, what is the probability the average miles will be more than 9500 miles?
.4812
.0188
.9812
.3372
16
A multiple choice test consists of 60 questions. Each question has 4 possible answers of which one is correct. If all answers are random guesses, estimate the probability of getting at least 20% correct.
0.1492
0.0901
0.8508
0.3508
17
Assume that women's heights are normally distributed with a mean of 63.6 inches and a standard deviation of 2.5 inches. If 90 women are randomly selected, find the probability that they have a mean height between 62.9 inches and 64.0 inches.
0.9318
0.0424
0.1739
0.7248
18
Two percent of CD-ROM drives produced in a certain plant are defective. Estimate the probability that of 10,000 randomly selected drives, at least 219 are defective.
0.0934
0.0823
0.0869
0.9066
0.4953
0.0202
0.0668
0.4332
Explanation / Answer
Solutions :
1. 0.0202
3. 0.9812
4. 0.0409
5. 0.0669
6. 0.7673
10. 0.2090
12. 0.0643
14. 0.0643
15. 0.0188
16. 0.8508
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