Question

a. If the confidence interval for the standard deviation is between 9 and 16 then the confidence interval for a variance will be between

81 and 256

9 and 16

3 and 4

-3 and -4

b. In a study of size 8 where the variance is unknown, and the population is normally distributed, the distribution that should be used to calculate confidence intervals is

a normal distribution

a t distribution with 7 degrees of freedom

a t distribution with 8 degrees of freedom

a t distribution with 6 degrees of freedom

Answer 1

a)

Confidence interval for standard deviation is

Confidence interval for variance

​​​​​​

For confidence interval for variance is square of standard deviation confidence interval

#confidence interval for a variance will be between 81 and 256

Option 1st is correct

#b)

Sample size is n=8

If variance is unknown hence we use t-test with degree of freedom (n-1) ie 7 df

t distribution with 7 degrees of freedom

Option a is correct