Need help with 11. . . .

Explanation:

You have the right idea, but keep in mind that it says consecutive even integers. So we're only looking at numbers like 2,4,6,8,... and these numbers must follow one right after another. If that "even" wasn't there, then your answer and steps would be 100% correct.

If x is an even number, then x+2 is the next even number, and x+4 is the one after that.

Add them up to get

(x)+(x+2)+(x+4)

x+x+2+x+4

(x+x+x)+(2+4)

3x+6

Then divide by 3 to compute the average

(3x+6)/3

3x/3 + 6/3

x+2

Set this average equal to 48 and solve for x

x+2 = 48

x = 48-2

x = 46 is the smallest number

x+2 = 46+2 = 48 is the middle value

x+4 = 46+4 = 50 is the largest

Note how the middle value is exactly the average. This is because we have symmetry going on here.

It's similar to how the average of the set {1,2,3} is 2 since 2 is in the middle.

Check:

add the values: 46+48+50 = 144

divide by three: 144/3 = 48

The average of the set {46,48,50} is 48

This confirms the answer

each side has a different length.  

step-by-step explanation: