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.
Answer:
8pi
Step-by-step explanation:
circumference of the circle=2 pi r(radius)
=2pi×d(diameter)/2
=2 × pi × 8/2
=8 pi cm
75% i would think if you subtract 25% from 100% of the class
Answer:
C.
Step-by-step explanation:
Circumference=PI*diameter
Circumference=3.14*19.5
Circumference=61.23 rounds to 61.2 so the answer is C