10 times the sum of 2 and 1 is represented by the following expression:
10 x (2 + 1)
10 x is ten times, and (2 + 1) the sum of 2 and 1, "10 times the sum of 2 and 1".
We have the formula

From the above formula,

That is variance of Y is 49 not 7.
Hence the statement is (b) False
He needs to cut 3/8 off because 3 1/8-2 3/4=3/8.