The best measure of the center is “median” this means middle number. The answer is 60.
Tip:
To find the median number organize the numbers from least to greatest, like this:
40 40 55 55 55 60 60 65 65 70 70 70
Now just cross the numbers in this order: right to left like this:
40 55 55 55 60 60 65 65 70 70
This way you should find the middle number. If you end up with two numbers as the middle you need to add them and divide by 2 to find the average of the two numbers.
Hope this helps!!
