Answer:

--- Variance
Step-by-step explanation:
Given

Solving (a): Calculate the mean.
The given data is a grouped data. So, first we calculate the class midpoint (x)
For 51 - 58.

For 59 - 66

For 67 - 74

For 75 - 82

For 83 - 90

So, the table becomes:

The mean is then calculated as:



-- approximated
Solving (b): The sample variance:
This is calculated as:

So, we have:


-- approximated
the answer i got was 50,000
if its not right i can try to figure it out again
Answer:
6
Step-by-step explanation:
All you need to do is add all 7 job hours, and divide the total by 7. Your answer should be 7
Answer:
(0,2.5)
Step-by-step explanation: