Answer: good luck
Step-by-step explanation:
Answer:
-78.12
Step-by-step explanation:
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 length of material needed for the border is the perimeter of the backyard play area
<h3>How to calculate the
length of
material needed </h3>
The area of the play area is given as:

The area of a trapezoid is calculated using:

Where L1 and L2, are the parallel sides of the trapezoid and H represents the height.
The given parameter is not enough to solve the length of material needed.
So, we make use of the following assumed values.
Assume that the parallel sides are: 25 feet and 31 feet long, respectively.
While the other sides are 10.2 feet and 8.2 feet
The length of material needed would be the sum of the above lengths.
So, we have:


Using the assumed values, the length of material needed for the border is 74.4 feet
Read more about perimeters at:
brainly.com/question/17297081