Your answer for the girls in the gymnastics club is correct.
Do the percentage of water the same way: Divide 139 by 197.
That'll give you the decimal amount that's covered by water.
To change the decimal to a percentage, move the decimal point
two places that way ==> .
In order to find the percent error, we need to first find the difference between what was expected and what is actually costed. We do this by subtracting:

So now we know that the expected amount was off by $63. To find the percent error, we need to take this $63, and divide it by the amount that was estimated. Let's do that now:

However this is in decimal form. We need to multiply by 100 in order to get it in a percent:

Now we know that
the percent error of the hospital bill estimate is 13.64%.
Answer:
test statistic (Z) is 2.5767 and p-value of the test is .009975
Step-by-step explanation:
: percentage of students who smoke did not change
: percentage of students who smoke has changed
z-statistic for the sample proportion can be calculated as follows:
z=
where
- p(s) is the sample proportion of smoking students (
=0.25)
- p is the proportion of smoking students in the survey conducted five years ago (18% or 0.18)
- N is the sample size (200)
Then, z=
≈ 2.5767
What is being surveyed is if the percentage of students who smoke has changed over the last five years, therefore we need to seek two tailed p-value, which is .009975.
This p value is significant at 99% confidence level. Since .009975 <α/2=0.005, there is significant evidence that the percentage of students who smoke has changed over the last five years