Probability Questions and Answers

The manager of a computer retails store is concerned that his suppliers have been giving him laptop computers with lower than average quality His research shows that replacement times for the model laptop of concern are normally distributed with a mean of 4 1 years and a standard deviation of 0 6 years He then randomly selects records on 54 laptops sold in the past and finds that the mean replacement time is 3 8 years Assuming that the laptop replacement times have a mean of 4 1 years and a standard deviation of 0 6 years find the probability that 54 randomly selected laptops will have a mean replacement time of 3 8 years or less P M 3 8 years Enter your answer as a number accurate to 4 decimal places Based on the result above does it appear that the computer store has been given laptops of lower than average quality Yes The probability of this data is unlikely to have occurred by chance alone O No The probability of obtaining this data is high enough to have been a chance occurrence

Raven invested some money in an account The balance in the account is given by the equation B 7900 120t where t is the number of years since the initial investment was made and B is the account balance The equation tells us that Raven started with account is Select an answer at a rate of in the account and that the balance in the Select an answer

Question 3 Suppose the amount of time it takes a Capt Rig announcement to touch down is uniformly distri a Find the probability that for a randomly sele the plane after the announcement Round to 1 b What is the longest landing time included in

d 7 Quiz for K Ques Find the critical value s for the Ho 20 0 05 n 15

d 7 Quiz for K Question 6 of Use the calculator displays to the right to m reject the null hypothesis at a significance l

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Quiz for Ques For which confidence interval fo

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low s your new car The General Social Survey reported that 92 of people who bought a car in the past five years were satisfied with their purchas low large a sample of car buyers needs to be drawn so that the sample proportion p who are satisfied is approximately normally distributed The sample size must be at least 63 X 5

Steel rods are manufactured with a mean length of 27 centimeter cm Because of variability in the manufacturing process the lengths of the rods are approximately normally distributed with a standard deviation of 0 06 cm Click the icon to view a table of areas under the normal curve www a What proportion of rods has a length less than 26 9 cm Round to four decimal places as needed

Assume that the random variable X is normally distributed with mean 60 and standard deviation a 7 Compute the probability P 56 X 66 Be sure to draw a normal curve with the area corresponding to the probability shaded Click here to view the standard normal distribution table page 1 Click here to view the standard normal distribution table page 2 CA 56 66 Q UB 5 The probability P 56 X 66 is 56 66 Q C 56 66 Round to four decimal places as needed D 56 60 Q

Assume the random variable X is normally distributed with mean u 50 and standard deviation o 7 Com probability Be sure to draw a normal curve with the area corresponding to the probability shaded P 34 X 58 Click the icon to view a table of areas under the normal curve 34 50 53 P 34 X 58 Round to four decimal places as needed 34 50 58 50 58

Find the Z scores that separate the middle 89 of the distribution from the area in the tails of the standard normal distribution Click the icon to view a table of areas under the normal curve The Z scores are Use a comma to separate answers as needed Round to two decimal places as needed

2 0 and c Z 0 16 and Z 0 75 Click the icon to view a table of areas under the normal curve normal curve that lies between a Z 0 87 and Z 0 www a The area that lies between Z 0 87 and Z 0 87 is 0 6157 Round to four decimal places as needed b The area that lies between Z 2 21 and Z 0 is Round to four decimal places as needed

Assume the random variable X is normally distributed with mean 50 and standard deviation o 7 Compute the probability Be sure to draw a normal curve with the area corresponding to the probability shaded P 52 x 68 Click the icon to view a table of areas under the normal curve Which of the following normal curves corresponds to P 52 x 68 O A B Q Q Q O C 27

Determine the area under the standard normal curve that lies between a Z 0 87 and Z 0 87 b Z 2 21 and Z 0 and c Z 0 16 and Z 0 75 Click the icon to view a table of areas under the normal curve a The area that lies between Z 0 87 and Z 0 87 is Round to four decimal places as needed Tables of Areas under the Normal Curve Ave TABLE V 2 00 01 07 34 01XX23 0 003 ons aans 0 0003 0 0003 0 0003 DIKKET 33 LOOKS OFERIS OLEKKYS 00004 0 0004 0 00004 0 0004 0 0004 11 0 0007 0 1007 0 0006 0 0006 GLOEDS 0 0006 0 0005 0 0005 aps 0 0008 0 0008 0 0008 0 0007 00012 0 0012 0 0011 00011 anto ao C 11 3 0 0 0013 00013 00013 20010 BOOK 0 1017 0 0016 0 0016 0 0015 ALOGES 000114 1100124 010023 0 0125 000121 AINEI OLIVERO 0 019 BIKER BUKITT Standard Normal Distribution 02 03 04 05 2 9 28 27 26 15 60000 PROUD 90 0 0019 000 GLOKA 0 0035 0234 0 00033 0002 000 0 0047 07045 01 0643 610041 1000 0 0079 CORINN 0 006 BLOODAG 0 0059 0 003s 0 0054 0 0052 24 0 0082 0 000 0 0078 0 0075 0 0073 0 0071 LSIKTO MEKET O 11000 42370 FOOD 08 XXID XX70 OCTATO LEXTO BLODE BOOM 0 0004