Answer:
b. 224
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
.
So it is z with a pvalue of
, so 
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.
In this problem:
We want to find n, when
So






The nearest integer number to 223.9 is 224.
So the correct answer is:
b. 224
Answer:
x=3(y-9)
Step-by-step explanation:
There will be 4 water stations.
Why?
3/4 = .75 as a decimal
Personally, I believe that it’s easier to use decimals, I can explain the way in fractions in the comments if you’d like, just ask.
Anyway, .75 • 4= 3
or 3 / .75 = 4 (division is easier with bigger numbers)
so, there will be 4 water stations, given that the one race is 3 miles long.
If this explanation seems unclear, I’d be happy to explain. Feel free to ask in the comments!! I’m happy to help.
Hope this helps!
(If you find this answer helpful, please consider marking me brainliest, Thanks!)