# Question

Eighty randomly selected batteries were tested to determine their lifetimes (in hours). The following frequency distribution was obtained.

Class boundaries Frequency

62.5–73.5..........5

73.5–84.5 .........14

84.5–95.5 .........18

95.5–106.5.........25

106.5–117.5..........12

117.5–128.5.........6

Can it be concluded that the lifetimes of these brands of batteries are consistent?

Find the variance and standard deviation.

Class boundaries Frequency

62.5–73.5..........5

73.5–84.5 .........14

84.5–95.5 .........18

95.5–106.5.........25

106.5–117.5..........12

117.5–128.5.........6

Can it be concluded that the lifetimes of these brands of batteries are consistent?

Find the variance and standard deviation.

## Answer to relevant Questions

Find the variance and standard deviation for the two distributions in Exercises 8 and 18 in Section 2–2. Compare the variation of the data sets. Decide if one data set is more variable than the other. Find the variance and ...The average age of the accountants at Three Rivers Corp. is 26 years, with a standard deviation of 6 years; the average salary of the accountants is $31,000, with a standard deviation of $4000. Compare the variations of age ...The average sale price of new one-family houses in the United States for 2003 was $246,300. Find the range of values in which at least 75% of the sale prices will lie if the standard deviation is $48,500. Use this data set: 10, 20, 30, 40, 50 a. Find the standard deviation. b. Add 5 to each value, and then find the standard deviation. c. Subtract 5 from each value and find the standard deviation. d. Multiply each value by 5 ...The average score on a state CDL license exam is 76 with a standard deviation of 5. Find the corresponding z score for each raw score. a. 79 b. 70 c. 88 d. 65 e. 77Post your question

0