Answer:
A sample of 179 is needed.
Step-by-step explanation:
We have that to find our
level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of
.
That is z with a pvalue of
, so Z = 1.44.
Now, find the margin of error M as such

In which
is the standard deviation of the population and n is the size of the sample.
A previous study found that for an average family the variance is 1.69 gallon?
This means that 
If they are using a 85% level of confidence, how large of a sample is required to estimate the mean usage of water?
A sample of n is needed, and n is found for M = 0.14. So






Rounding up
A sample of 179 is needed.
The correct answer is C. This is because
10^-2 = 1/10^2 which is 0.01
100 meters is -1°C
1,000 meters is -10°C
10,000 meters is -100°C
And 2,000 meters is -20°C
12Km is 12,000 meters
12,000 meters is -120°C
Your answer is -120°C
-IronWolfX
Divide 3.24 with 6 and the answer will be found
$0.54
9.889 more words so i can post this