Question

- Following are the fuel efficiency, in miles per gallon, for a sample of convertibles. Calculate the sample variance. 25, 23 , 25, 20, 21 Write only a number as your answer.

Round to one decimal place (for example: 8.3).

- Following are playback time, in hours, for a sample of MP3 players, Calculate the sample standard deviation. 23,35,28,18,25,21,37,28 Write only a number as your answer. Round to two decimal place (for example: 8.32).

- Following are closing prices of Google stock for a sample trading days. Use the 1-Var Stats command in the TI-84-Plus calculator to compute the sample standard deviation,

441.19,482.37,483.19,478.50,475.10,472.08,444.95,481.86

Write only a number as your answer. Round to two decimal place (for example: 8.32).

- In a large sample of customer accounts, a utility company determined that the average number of days between when a bill was sent out and when the payment was made is 12 with a standard deviation of 19 days. Assume the data to be approximately bell shaped. Approximately 95% of all customer accounts have the average number of days between two values A and B.What is the value of B? Right only a number as your answer

- A Study studied The birth weight of 2997 babies born in the United States. The main weight was 3234 grams with a standard deviation of 871 grams. Assume that birthweight data are approximately bell shaped. Estimate the number of newborns who weighed between 1492 grams in 4976 grams. Write only a number as your answer. Round your answer to the nearest whole number

- The GMAC insurance company reported that the mean score on the national drivers test was 81.4 with a standard deviation of 3.1 points. The test scores are approximately bell shaped. Approximately 68% of all test scores were between two values A & B. What is the value of a? Write only A number as your answer. Round to one Decimal Place.

Answer 1

1. For the given sample mean

Create the following table.

data	data-mean	(data - mean)2
25	2.2	4.84
23	0.2	0.04
25	2.2	4.84
20	-2.8	7.84
21	-1.8	3.24

Find the sum of numbers in the last column to get.

So Variance is

2. For the given data sample mean is

Create the following table.

data	data-mean	(data - mean)2
23	-3.875	15.015625
35	8.125	66.015625
28	1.125	1.265625
18	-8.875	78.765625
25	-1.875	3.515625
21	-5.875	34.515625
37	10.125	102.515625
28	1.125	1.265625

Find the sum of numbers in the last column to get.

So standard deviation is