Answer:
$91.76
Step-by-step explanation:
Interest the first month was ...
I = Prt
I = $15000(0.0387)(1/12) = $48.375 ≈ $48.38
Interest in the second month was ...
I = $15000(0.0347)(1/12) = $43.375 ≈ $43.38
So the total interest amount is ...
$48.38 +43.38 = $91.76
Marcella earned $91.76 in two months.
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Comment on rounding
We have assumed that Marcella's account statement will report the interest rounded to 2 decimal places (cents). Hence she obtains the benefit from rounding for both months.
If there is no statement, so that rounding is not required until the end of the second month, then she may not have that extra penny in her account.