Let width = x then
2x+ 2(x + 2) = 80
4x + 4 = 80
4x = 76
x = 19
so the width is 19 and the length is 21 answer
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
Because you if it changes its a function
To calculate mean: Just add up all the numbers, then divide by how many numbers there are.345 + 673 + 728 +775 + 822 +827 +839 + 951 = 5960/8 = 745
633 + 673 + 728 +775 + 822 +827 +839 + 951 = 6248/8 = 781781- 745 = 35 It increases by 35To find the Median, place the numbers in value order and find the middle. BUT, with an even amount of numbers things are slightly different. In that case we find the middle pair of numbers, and then find the value that is half way between them. This is easily done by adding them together and dividing by two. 345 673 728 775 822 827 839 951 The median = 822-775 /2
The median =23.5After the change633 673 728 775 822 827 839 951 The median = 822-775 /2
The median =23.5The median stays the same.
<span>9c+(8+3c)
9c+8+3c (collect like terms)
9c+3c+8
12c+8
12c+8 is the answer.
im not sure if your teacher also wants the answer to be in simplest form so im going to do that below as well:
12c+8 (4*3=12 and 4*2=8. you can take out a 4 from those 2 numbers)
4(3c+2) (this is the simplest form of </span>9c+(8+3c)<span>)
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