Elapsed time worksheet with answers, including time intervals and a timer problem.

The image you've uploaded is an "Elapsed Time Worksheet 4 Answers" from Math-Salamanders.com, which provides solutions to three elapsed time problems. Let's go through each section and explain the solutions step by step.

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🔹 Problem 1: Work out the elapsed time between the two times

We are given a start time and an end time, and we need to calculate how much time has passed (elapsed time).

#### ✔ How to calculate:
- Subtract the start time from the end time.
- If the minutes of the "to" time are less than the "from" time, borrow 1 hour (60 minutes) from the hours.

Let’s verify one example:

> Example: From 13:05 to 18:30
> - Hours: 18 – 13 = 5 hours
> - Minutes: 30 – 5 = 25 minutes
> → 5 hours 25 minutes ✔

Now let’s check all:

| From | To | Elapsed Time |
|------|----|--------------|
| 13:05 | 18:30 | 18:30 – 13:05 = 5h 25m ✔ |
| 11:45 | 15:30 | 15:30 – 11:45 = 3h 45m ✔ |
| 14:15 | 20:50 | 20:50 – 14:15 = 6h 35m ✔ |
| 12:40 | 16:05 | 16:05 – 12:40 = 3h 25m ✔ |
| 07:20 | 13:15 | 13:15 – 07:20 = 5h 55m ✔ |
| 17:45 | 21:20 | 21:20 – 17:45 = 3h 35m ✔ |
| 22:40 | 06:30 | This crosses midnight!
→ 24:00 – 22:40 = 1h 20m
Then 06:30 – 00:00 = 6h 30m
Total: 1h 20m + 6h 30m = 7h 50m ✔

✔️ All answers in this section are correct.

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🔹 Problem 2: Fill in the missing times on the chart

We are given either the start time or end time and the elapsed time. We must find the missing one.

#### ✔ Method:
- If Time From and Elapsed Time are known → Add to get Time To
- If Time To and Elapsed Time are known → Subtract to get Time From

Let’s verify each row:

1. From: 09:40, Elapsed: 1h 40min
→ 09:40 + 1h = 10:40, then +40min = 11:20 ✔

2. To: 13:25, Elapsed: 3h 20min
→ 13:25 – 3h = 10:25, then –20min = 10:05 ✔

3. To: 18:10, Elapsed: 2h 30min
→ 18:10 – 2h = 16:10, then –30min = 15:40 ✔

4. From: 08:20, Elapsed: 5h 45min
→ 08:20 + 5h = 13:20, then +45min = 14:05 ✔

5. From: 14:35, Elapsed: 4h 30min
→ 14:35 + 4h = 18:35, then +30min = 19:05 ✔

✔️ All filled-in times are correct.

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🔹 Problem 3: A timer goes off at 08:40 and every 35 minutes until 12:10

We need to list all times the timer goes off starting at 08:40, adding 35 minutes each time, up to 12:10.

#### ✔ Step-by-step addition:

Start: 08:40

1. 08:40 + 35 min = 09:15
2. 09:15 + 35 min = 09:50
3. 09:50 + 35 min = 10:25
4. 10:25 + 35 min = 11:00
5. 11:00 + 35 min = 11:35
6. 11:35 + 35 min = 12:10 ✔ (stop here)

So the times are:
08:40, 09:15, 09:50, 10:25, 11:00, 11:35, 12:10

✔️ The answer shown in red matches perfectly.

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✔ Final Summary:

All answers provided in the worksheet are correct. Here’s a quick recap:

1. Elapsed time calculations are accurate using subtraction with borrowing when needed.
2. Missing times are correctly filled by adding or subtracting elapsed time.
3. Timer sequence is correctly generated by repeatedly adding 35 minutes.

This worksheet is a great practice tool for understanding time intervals and arithmetic with hours and minutes.

Let me know if you'd like a printable version or want to create similar problems!