C=pi*d
=22/7*7
=22
22 is the circumference of first circle
Answer:

Step-by-step explanation:
Since these angles are supplementary, they add up to 180°.
Let's make an equation.

Answer:
The need to sample 76 days.
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.
How many days do they need to sample
We need to sample n days.
n is found when M = 300.
We have that 
So




Rounding up
The need to sample 76 days.