Estimate its sum to the nearest ten
( 57+34 )
=​

the sum would be 90 rounded to the nearest ten.

ANSWER:

Sum of the given two numbers,

57 + 34 = 91

Now, the one's digit is less than 5.

So, Estimated number is 90.

The outlier of 2 decreases the mean chapter-page count from the center.

Explanation:

A very small outlier will decrease the mean.  This is because the mean is found by first adding together all of the data values; when we add a small value, this does not increase the sum.  The sum is then divided by the number of data points; when we do this, the mean is smaller.