Week 7 Quiz Notes

 Essay in Week 7 Quiz Remarks

п»їMath 221

Quiz Review for Weeks 5 and 6

1 ) Find the region under the standard normal competition between z = 1 . 6 and z = 2 . 6th. First we look for the location of both by doing " 2nd, Vars, NORMALCDF” and inputting " -1000, " Z, ” 0, 1 then find the difference between both.

installment payments on your A business wants to estimate the real mean annual income of its customers. В It arbitrarily samples 230 of it is customers. В The imply annual income was $61, 500 with a common deviation of $2, two hundred. В Look for a 95% confidence interval pertaining to the true indicate annual income with the business' consumers. First we find E getting into Zc(standard deviation/square root of volume of trials. ) Now we add and subtract that number from the suggest income to find both endpoints. The Zc of 95% is 1 ) 96 thus we would perform 1 . 96((2200)/square root of 220) giving all of us 290. 71. Now whenever we subtract that from the imply income, we have 61109. up to 29 as the left endpoint and 61690. 71 because the right endpoint.

3. IQ test ratings are normally allocated with a indicate of 95 and a typical deviation of 15. Could be IQ score is found being 120. Find the z-score corresponding to this value. " X-mean/standard change. (120-100)/15

4. Two high school students took equal language checks, one in German born and one in French. The student taking the German born test, that the mean was sixty six and the common deviation was 8, won an 82, while the student taking the French test, for which the imply was twenty seven and the standard deviation was 5, scored a thirty-five. Compare the scores. Same equation because the question previously mentioned to find the corresponding z-score. two would be better.

5. A company wants to estimate the true imply annual income of its buyers.  The business needs to be within just $250 in the true indicate.  The business enterprise estimates the real population common deviation is about $2, 500. If the confidence level is 90%, find the mandatory sample size in order to meet the desired reliability. first we find the Unces score to get the percentage which usually ends up getting 1 . 645. Then all of us multiply that times the conventional deviation and divide that by the error, in this case getting " 250” and sq . the final response. Therefore we have 1 . 645(2400)/250 squared which will equals 249. 38 and that we need regarding 250 to find the desired effects.

6. The distribution of cholesterol levels in young boys is approximately normal with mean sama dengan 170 and standard change = 40 (Source: U. S. Nationwide Center intended for Health Statistics). Levels previously mentioned 200 warrant attention. Locate the likelihood that a adolescent boy provides a cholesterol level greater than 2 hundred.

7. An airline is aware of from encounter that the division of the volume of suitcases that get lost each week on a selected route is approximately normal with mean = 15. five and standard deviation = 3. six. What is the probability that during a given week the airline will lose between 12 and 20 suitcases? To get the Z ratings, we take equally situations, take away the imply and separate by the regular deviation. Consequently we have (10-15. 5)/3. 6 and (20-15. 5)/3. 6th. To find the place, we make use of the calculators " Vars, usual cdf” function and find the between the two.

8. A car safety professional wants to estimation the suggest cost to repair a Chevy Corvette involved with a 35 mile each hour head-on collision. В The engineer fails 24 Corvettes and discovers the mean damage is $11, five-hundred with a standard deviation of $2, seven-hundred. В Look for a 98% confidence interval pertaining to the true mean cost to fix this type of car. Population indicate = 11500 +/- 2 . 500 * 2700/sqrt(24) sama dengan 11500 +/- 1377. 84. В Subtracting 1377. 84 gives a lower bound of 10122. sixteen. В Adding 1377. 84 gives a great upper certain of 12877. 84.

9. A expertise test has scores having a mean of 80 and a standard change of 12. A histogram of the data shows that the distribution is normal. Use the Scientific Rule to find the percentage of scores among 70 and 90.

15. An auditor wants to estimate what percentage of a bank's commercial loan files will be incomplete. В The auditor wants to become within 11% of the the case proportion whenever using a 90%...

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