Express the confidence interval 3.8% <p< 17.2% in the form of p^ +- E.

Question

Express the confidence interval 3.8% <p< 17.2% in the form of p^ +- E.

__% +- %__

Answer 1

Hi Anni,

You need the value directly in the middle of the interval, which will become p^. It will be easier to work with whole numbers initially, but remember we must divide by 100 at the end:

First, get the width of the interval:

17.2 - 3.8 = 13.4

Divide by 2:

13.4/2 = 6.7. This is the error.

Add this to the lower bound--this will become p^:

3.8 + 6.7 = 10.5

Adding 6.7 to this will give the upper bound, 17.2.

Now, this gives:

CI= 10.5 +/- 6.7, but remember, these were percentages, so we divide by 100:

CI= 0.105 +/- 0.067

I hope this helps.