I’m almost done solving this
The "rule of 72" says that the doubling time in years is approximately 72 divided by the interest rate in percent. To make the money grow by a factor of 4 requires that it double twice, so will take twice as long as the period to double once.
2×72/11.3 ≈ 12.7 . . . . years
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The "rule of 72" is an approximation. The actual quadrupling time for this interest rate and compounding is about 12.6 years. (The actual product of doubling time and nominal interest rate is about 71.25.)
Since Timothy collected more, we take the amount Timothy collected and subtract the amount Eric collected from that.

That means Timothy collected .5 kilograms more candy than Eric.
It is 32in^2 because 8x4 is 32