Bob Nale is the owner of Nale’s Quick Fill. Bob would like to estimate the mean number of gallons of gasoline sold to his customers. Assume the number of gallons sold follows the normal distribution with a population standard deviation of 1.90 gallons. From his records, he selects a random sample of 45 sales and finds the mean number of gallons sold is 5.70.a.What is the point estimate of the population mean? (Round your answer to 2 decimal places.)   Point estimate    b.Determine a 90% confidence interval for the population mean. (Use z Distribution Table.) (Round your answers to 2 decimal places.)   Confidence interval and

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Asked Nov 17, 2019
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Bob Nale is the owner of Nale’s Quick Fill. Bob would like to estimate the mean number of gallons of gasoline sold to his customers. Assume the number of gallons sold follows the normal distribution with a population standard deviation of 1.90 gallons. From his records, he selects a random sample of 45 sales and finds the mean number of gallons sold is 5.70.

a.

What is the point estimate of the population mean? (Round your answer to 2 decimal places.)

 

  Point estimate    

 

b.

Determine a 90% confidence interval for the population mean. (Use z Distribution Table.) (Round your answers to 2 decimal places.)

 

  Confidence interval  and     
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Expert Answer

Step 1

 

a.

It is given that,

Sample mean, x-bar = 5.70.

Population standard deviation, sigma is 1.90.

The sample size, n is 45.

The point estimate of the population mean is the sample mean.

Thus, the point estimate of µ is 5.70.

Step 2

b.

The z table value is found from the...

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Standard Normal Probabilities Table entry Table entry for z is the area under the standard normal curve to the left of z. 06 07 .08 .00 01 02 03 04 09 5080 5478 5871 5199 5239 5279 5319 5359 0.0 0.1 5000 5040 5438 .5832 5120 .5517 $910 .5160 5557 .5948 5636 5398 5793 5596 5987 5675 5714 5753 6026 0.25 0.3 6064 6103 6480 6844 6141 6368 6179 .6217 6255 .6293 .6331 6700 .6406 6443 .6517 6808 7157 6628 6985 7324 0.4 6554 6591 6664 6736 7088 6772 7123 6879 7224 6950 7291 7190 0.5 6915 7019 7357 7054 7389 7422 7454 7486 7517 7549 0.6 7257 7852 8133 8389 8621 0.7 7580 7611 7642 7939 7673 7704 7734 8023 7764 8051 7794 7823 0.8 7881 7910 7967 7995 8264 8078 8106 8159 8413 8186 8238 8485 8289 8531 8340 0.9 8212 8315 8554 8365 8508 8729 8925 8577 8599 1.0 8438 8665 8869 8461 8686 8830 9015 8708 8749 8770 8790 8810 1.1 1.2 8643 8849 8962 8980 8888 8907 8944 8997 1.3 9032 9192 9049 9207 .9066 .9082 .9099 9115 .9131 9147 9162 .9306 9177 9222 9357 9474 9236 9370 9251 9265 9279 9292 9319 14 9382 9495 9441 9545 1.5 9332 .9345 9463 9394 9406 9418 9525 9429 9484 9505 9515 9535 1.6 1.7 9452 .9554 9564 9573 9582 9591 9599 9608 9616 9625 9633 9706 9699 .9761 18 1.9 9641 9649 9656 .9664 .9732 9671 9678 .9686 9693 9713 9772 9719 9778 9738 9793 9756 9767 .9726 9744 .9750 9788 9834 2.0 9783 9830 9798 9842 9803 9808 9850 9812 9854 9817 9857 9826 9864 9896 9920 9838 9875 9904 9846 2.1 2.2 9821 9861 .9893 9868 9881 9871 9878 9906 9929 9884 9887 9890 9916 9936 2.3 9898 .9901 9909 9931 9911 9932 9913 9934 2.4 9918 9922 .9925 .9927 9948 9961 9971 2.5 2.6 2.7 9938 9940 9941 .9943 .9945 9946 .9949 9951 9952 9953 9965 9957 9968 9962 9972 9979 .9985 9963 9973 9955 9966 9956 9967 9959 9960 9964 9969 9970 9974 9975 9977 9979 .9985 2.8 9974 9976 9977 9978 9980 9986 9981 9986 2.9 .9981 9982 9982 .9983 .9984 9988 9984 9989 3.0 3.1 3.2 9987 9989 9989 9990 9993 9990 9993 9987 9990 9987 9991 9988 9991 .9992 9994 9992 9994 .9991 9992 9994 .9992 9993 9995 9993 9995 9994 9994 9995 9995 9995 9996 9997 3.3 9995 9996 9996 9997 9996 .9996 9996 9997 9997 9997 9998 3.4 9997 9997 9997 9997 9997

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