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Quiz-2-Spring20181.docxSTAT 200 6363, Spring 2018
UMUC
Quiz-2
Show your work on all problems. Submit the completed quiz in the assignment folder. Only an answer will not earn any points.
Total Points: 85
Due: February 19, 2018 23
1. The systolic blood pressure of eighteen-year-old women is normally distributed with mean of 120 mmHg and standard deviation of 12 mmHg. What percentage of eighteen-year-old women has a systolic blood pressure between 96 mmHg and 144 mmHg? [10]
2. The number of hours per day a college student spends on homework has a mean of 4 hours and a standard deviation of 1.25 hours. Yesterday, Sari spent 2 hours on homework. How many standard deviations from mean is that? [10]
3.
s =44. [10]
4. The following table contains data from a study of two airlines which fly to Small Town, USA. [5]
|
|
Number of fights which were on time |
Number of flights which were late |
|
Podunk Airlines |
33 |
6 |
|
Upstate Airline |
43 |
5 |
If one of the 87 flights is randomly selected, find the probability that the flight selected is an Upstate Airlines flight which was on time.
Answer questions 5, 6 and 7 based on the following information.
The IQ scores are normally distributed with a mean of 100 and a standard deviation of 15.
5. What is the probability that a randomly person has an IQ between 85 and 115? [10]
6. Find the 90th percentile of the IQ distribution. [10]
7. If a random sample of 100 people is selected, what is the standard deviation of the sample mean? [5]
8. A random sample of 225 SAT scores has a mean of 1522. Assume that SAT scores have a standard deviation of 300. Construct a 95% confidence interval estimate of the mean SAT scores. [10]
9. A 6-faced die is rolled two times. Let A be the event that the outcome of the first roll is greater than 4. Let B be the event that the outcome of second roll is an odd number.
What is the probability that the outcome of the second roll is an odd number, given that the first roll is greater than 4? [5]
10. A random sample of 225 SAT scores has a sample mean of 1500. Assume that SAT scores have a population standard deviation of 300. Construct a 95% confidence interval estimate of the mean SAT scores. Show all work. Just the answer, without supporting work, will receive no credit. [10]
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