Question

The world's smallest mammal is the bumblebee bat. The mean weight of 100 randomly selected bumblebee bats is 1.659 grams, with a standard deviation of 0.264 grams.

Find a 99.9% confidence interval for the mean weight of all bumblebee bats at the following confidence levels (two places after decimal): (WebAssign will check your answer for the correct number of significant figures. , WebAssign will check your answer for the correct number of significant figures. )

Find a 99% confidence interval for the mean weight of all bumblebee bats at the following confidence levels (two places after decimal): (WebAssign will check your answer for the correct number of significant figures. , WebAssign will check your answer for the correct number of significant figures. )

Find a 95% confidence interval for the mean weight of all bumblebee bats at the following confidence levels (two places after decimal): (WebAssign will check your answer for the correct number of significant figures. , WebAssign will check your answer for the correct number of significant figures. )

Find an 80% confidence interval for the mean weight of all bumblebee bats at the following confidence levels (two places after decimal): (WebAssign will check your answer for the correct number of significant figures. , WebAssign will check your answer for the correct number of significant figures. )

Answer 1

using excel we have

Confidence Interval Estimate for the Mean
Data
Sample Standard Deviation	0.264
Sample Mean	1.659
Sample Size	100
Confidence Level	99.9%
Intermediate Calculations
Standard Error of the Mean	0.0264
Degrees of Freedom	99
t Value	3.3915
Interval Half Width	0.0895
Confidence Interval
Interval Lower Limit	1.57
Interval Upper Limit	1.75

a 99.9% confidence interval for the mean weight of all bumblebee bats is 1.57 to 1.75

Confidence Interval Estimate for the Mean
Data
Sample Standard Deviation	0.264
Sample Mean	1.659
Sample Size	100
Confidence Level	99%
Intermediate Calculations
Standard Error of the Mean	0.0264
Degrees of Freedom	99
t Value	2.6264
Interval Half Width	0.0693
Confidence Interval
Interval Lower Limit	1.59
Interval Upper Limit	1.73

a 99% confidence interval for the mean weight of all bumblebee bats is 1.59 to 1.73

Confidence Interval Estimate for the Mean
Data
Sample Standard Deviation	0.264
Sample Mean	1.659
Sample Size	100
Confidence Level	95%
Intermediate Calculations
Standard Error of the Mean	0.0264
Degrees of Freedom	99
t Value	1.9842
Interval Half Width	0.0524
Confidence Interval
Interval Lower Limit	1.61
Interval Upper Limit	1.71

a 95% confidence interval for the mean weight of all bumblebee bats is 1.61 to 1.71

Confidence Interval Estimate for the Mean
Data
Sample Standard Deviation	0.264
Sample Mean	1.659
Sample Size	100
Confidence Level	80%
Intermediate Calculations
Standard Error of the Mean	0.0264
Degrees of Freedom	99
t Value	1.2902
Interval Half Width	0.0341
Confidence Interval
Interval Lower Limit	1.62
Interval Upper Limit	1.69

a 80% confidence interval for the mean weight of all bumblebee bats is 1.62 to 1.69