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The question from the first image asks to calculate the time Zohri would take to run 30 laps around the track if he is running at a speed of 20 km/h. Let's break it down:

1. **Track Length**: From the diagram, the track consists of two straight sections (28 meters each) and two semicircles (with a diameter of 28 meters, so each semicircle has a length of \( \pi \times 28 / 2 = 44 \, m \) approximately).

   Total track length:
   \[
   L = 2 \times 28 \, \text{m} + 2 \times 44 \, \text{m} = 56 \, \text{m} + 88 \, \text{m} = 144 \, \text{m}
   \]

2. **Convert Speed to m/s**:
   Zohri's speed is 20 km/h, which is:
   \[
   20 \, \text{km/h} = \frac{20 \times 1000}{3600} \, \text{m/s} = 5.56 \, \text{m/s}
   \]

3. **Time per Lap**:
   Time to complete one lap (144 m) at 5.56 m/s:
   \[
   t_{\text{lap}} = \frac{144 \, \text{m}}{5.56 \, \text{m/s}} \approx 25.9 \, \text{seconds}
   \]

4. **Total Time for 30 Laps**:
   \[
   t_{\text{total}} = 30 \times 25.9 \, \text{seconds} = 777 \, \text{seconds} \approx 12.95 \, \text{minutes}
   \]

Since the closest time given in the options is **13 minutes**, and rounding error could account for a slight difference in interpretation or rounding, the answer is closest to **B. 15 minutes**.

Would you like further details, or have any additional questions?

Here are 5 related questions to consider:
1. How would the time change if Zohri increased his speed by 5 km/h?
2. How long would Wibowo or Yudhi take if they ran at half Zohri's speed?
3. What if the track was 10 meters longer? How would that affect Zohri's time?
4. How can you calculate the total distance Zohri runs in 30 laps?
5. How many laps could Zohri complete in 10 minutes at the same speed?

**Tip**: Always double-check unit conversions, especially with time and speed, as small errors can lead to significant differences in results.

Apabila Zohri berlari dengan kecepatan 20 km/jam pada lintasannya sebanyak 30 putaran, maka waktu yang ditempuh Zohri sekitar ... menit

Learn how to calculate the time Zohri takes to complete 30 laps on a 144 m track at a speed of 20 km/h. This problem involves key concepts like distance, speed, and time relationships. The final time is approximately 13 minutes. Suitable for Grades 9-12 students.

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