Let's break down the problem and find out how long the pie should have been heated.

1. Initial Conditions and Mistake:

   • The instructions require the pie to be heated for more than 4 minutes.
   • Michael inputs the time as a three-digit number representing minutes and seconds, but the microwave interprets this input as seconds.
   • The microwave ends up heating the pie for 60% longer than required.

2. Let $t$ be the required heating time in seconds.
   Since the microwave heats the pie for 60% longer, the actual heating time $t_{\text{actual}}$ is given by: $t_{\text{actual}} = t + 0.6t = 1.6t$

3. Determining the Actual Heating Time:
   Suppose Michael inputs the time as $xyz$ (in minutes and seconds), where $x$ represents the hundreds digit, $y$ the tens digit, and $z$ the units digit. The microwave interprets this as $100x + 10y + z$ seconds.

4. Calculating the Required Heating Time:
   The required time is $t$, and the actual time is $1.6t$. Given that Michael's input results in $100x + 10y + z$ seconds, we have: $1.6t = 100x + 10y + z$

5. Solving for $t$:
   Since $1.6t$ represents the actual time in seconds and $t$ represents the required time, we rearrange to find $t$: $t = \frac{100x + 10y + z}{1.6}$

Now, we need to find the valid inputs for $x, y, z$ that satisfy these conditions:

• The total time in minutes and seconds must be more than 4 minutes (i.e., more than 240 seconds).

Let's consider the possible values:

• The minimum three-digit number that exceeds 240 when interpreted as seconds must be considered since $t_{\text{actual}} = 1.6t$ must also be at least 240 seconds.

We will calculate it by trial to ensure consistency with the problem statement.

\text{For } & x = 2, y = 4, z = 0: \\ 1.6t &= 240 \\ t &= \frac{240}{1.6} = 150 \text{ seconds} \\ \end{align*}$$ This solution satisfies the condition that the actual time $$1.6t$$ (240 seconds) is a valid microwave interpretation. Thus, the required time $$t$$ should have been **150 seconds** or **2 minutes and 30 seconds**. ### Additional Questions and Tip 1. If the heating time was 3 minutes and 15 seconds, how long did the microwave actually heat the pie? 2. What is the percentage difference between the required and the actual heating time? 3. If the pie had been heated for 5 minutes and 20 seconds as required, how long would the microwave have actually heated it? 4. How many seconds longer than required did the pie actually heat? 5. If the microwave adds 60% more time to the actual time entered, how can we calculate the required time in seconds from the actual time? 6. What would happen if the input time was less than 4 minutes? How would it affect the actual heating time? 7. How can Michael ensure that the microwave heats the pie correctly next time? 8. If the actual heating time is given, how can you determine the time entered by Michael in the microwave? **Tip**: Always double-check the microwave's time format to ensure the input matches the required heating time, especially when converting between minutes and seconds.