Answer:



Explanation:
Week 1: 345 Week 2: 340 Week 3: 400 Week 4: 325
Step 1
In order to calculate the mean we need to use this formula:

And if we replace we got this:

Step 2
We can calculate the deviation from the mean by subtracting the mean for each value like this:
Week 1: 345-352.5=-7.5
Week 2: 340-352.5=-12.5
Week 3: 400-352.5=47.5
Week 4: 325-352.5=-27.5
Step 3
Now we can square each deviation to remove the negative signs like this:
Week 1: 345-352.5=(-7.5)^2=56.26
Week 2: 340-352.5=(-12.5)^2=156.25
Week 3: 400-352.5=(47.5)^2=2256.25
Week 4: 325-352.5=(-27.5)^2=756.25
Step 4
Now we need to do this operation:
If we want to find the popularion deviation we need to divide by n

If we want to find the sample deviation we need to divide by n-1

Step 5
Now we just need to take the root from step 4 in order to find the deviation:

