Question

A company has developed a new battery, but the average lifetime is unknown. In order to estimate this average, a sample of 21 batteries is tested and the average lifetime of this sampled batteries is 889 hours and sample standard deviation is 23.5 hours. Here the population of interest is: Olifetime of newly developed batteries O average 21 batteries, which were tested all newly developed batteries by the company Sutorit Answer Tries 0/2 Here the sample is: lifetime of newly developed batteries 21 batteries, which were tested average of 889 hours not in the list Submit Answer Tries 0/2 Here the variable of interest is: 21 batteries, which were tested lifetime of newly developed batteries O average O not in the list Submit Answer Tries 0/2 What is the parameter of interest in this case? no parameter is involved in this problem O average lifetime of 21 batteries tested average of all newly developed batteries by the company 21 batteries sampled and tested Submit Answer Tries 0/2 The sample standard deviation of 23.5 hours is the value of: an identifier a statistic a sample a parameter Submit Answer Tries 0/2 Here, the value of standard error of sample mean is 23.5 O 5.1281 6.493 Submit Answer Tries 0/2 The 78% confidence interval of mean battery life is: O (882.507 895.493) O (884.96 , 893.04) (882.71 ,895.29) Submit Answer Tries 0/2

Answer 1

the population of interest is the lifetime of newly developed batteries

Here the sample is 21 betteries which are tested

here the variable of intreast is the lifetime of newly developed batteries

paremeter of intreast is average lifetime of 21 betteries which are tested .

the sample standard deviation is a statistic

using minitab>stat>basic stat>one sample t

we have

One-Sample T

N Mean StDev SE Mean 78% CI
21 889.00 23.50 5.1281 (882.507, 895.493)

the value of standard error is 5.1281

the 98% confidence interval is (882.507, 895.493)