Plase theo deposited $1,250 in a savings account that pays 6% interest, compound quarterly. what was his balance at the end of the second quarter after the interest had been added? a. $1,270.31 b. $1,270.65 c. $1,290.62 d. $1,287,78 explain your answer clearly! and explain how you got it!

The account pays 6% interest per year.
The interest is compounded quarterly, or 4 times per year. That means at the end of each quarter year (3 months), he gets 3-months worth of interest added to the principal amount.
Since the interest is added each quarter, and since the yearly interest rate is 6%, the interest earned in 1 quarter is 6%/4 =1.5%. In 1 quarter (3 months), he earns 1.5%.

Start with $1250.
At the end of the first quarter, he earned 1.5% interest.
$1250 + 1.5% * $1250 = $1250 + 0.015 * $1250 = $1250 + $18.75 =
$1268.75
At the end of the first quarter he now has $1268.75.

Now he will earn interest for the second quarter.
He starts with $1268.75 and will earn 1.5% interest on that.
We do the same calculation we did above, but we start with $1268.75.
$1268.75 + 1.5% * $1268.75 = $1268.75 + 0.015 * $1268.75 = $1268.75 + $19.03 = $1287.78

The answer is $1287.78