Question

Using an independent-measures t, the 90% confidence interval for the difference between two population means ranges from 19 to 23. Based on this confidence interval, you can conclude that the difference between the two sample means is ____.a) 4 pointsb) 19 pointsc) 21 pointsd) 23 points

Answer 1

b

Explanation:

Answer 2

b

Explanation:

We must determine the the x value at 90% confidence interval. We find this from a table relating confidence intervals and x values. For 90%, z is 1.645.

WE must determine the mean of 19 and 23:

`=(19+23)/2=21`

We must determine the standard deviation. We let n be the number of population which is 2. We need to take the numbers 19 and 23 and subtract each by the mean and square the answer:

`(19-2)^2=289`

`(23-2)^2=441`

We then determine the mean of these two values as:

`(289+441)/2=365`

Now we take the square root of 365:

`√(365)=19.1`

The standard deviation is 19.1

The answer is b