Interest Problem

A Building society offered an interest rate of 7.25% p.a. on any investment over $3000. Mary deposited $3600 and received $5944 after 7 years.

a) How often was the interest compounded b) What simple interest rate would have given the same return in the same time? Round your answer to 1 decimal place. c) Mary was a little disappointed because she'd calculated a return of $5971. Her calculations were based on an incorrect assumption. What was that assumption?

I really need help with this problem. I've been stuck on it for a couple of hours but I can't figure out how to get to the answers. btw the answers are meant to be; a) every 4 months, b) 9.3% p.a., c) monthly compounding

Easy Math Editor

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Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$