Suppose that a customer service center claims that the telephone calls it receives last 114 seconds on average, with a standard deviation of 9 seconds. If you took a sample of 324 telephone calls, which of the following mean times would be within the 95% confidence interval?

A. 114.5 seconds
B. 115.5 seconds
C. 117.5 seconds
D. 116.5 seconds

Question

Suppose that a customer service center claims that the telephone calls it receives last 114 seconds on average, with a standard deviation of 9 seconds. If you took a sample of 324 telephone calls, which of the following mean times would be within the 95% confidence interval?

A. 114.5 seconds
B. 115.5 seconds
C. 117.5 seconds
D. 116.5 seconds

ganeshie8 · Answer

As a start : work out the margin of error

hockeychick23 · Answer

ok thanks i had started this problem earlier with perl but never finished it, i got to the point where i had 2 equations:114-.98= 113.02 and .98+114= 114.98 but didn't know where to go from there

ganeshie8 · Answer

those are the bounds of confidence interval

ganeshie8 · Answer

$$\large  (113.02,~~  114.98)$$

ganeshie8 · Answer

Look at the options, which option is in this range ?

hockeychick23 · Answer

114.5?

ganeshie8 · Answer

which number in the options is between 113.02 and 114.98 ?

ganeshie8 · Answer

Yes!

hockeychick23 · Answer

ok thanks!!

ganeshie8 · Answer

yw!

anonymous · Answer

Wrong it's 112.5