Let's solve the problem step by step.
---
Problem Statement:
- A
passenger train leaves the station and travels at
29.2 km/h.
-
2.4 hours later, a
cattle train leaves the same station, traveling in the
same direction at
36.5 km/h.
- We are to find:
How long did the passenger train travel before the cattle train caught up?
---
Step 1: Define Variables
Let:
- $ t $ = time (in hours) that the
cattle train traveled until it caught up with the passenger train.
Then, since the passenger train left
2.4 hours earlier, it has been traveling for:
- $ t + 2.4 $ hours when the cattle train catches up.
---
Step 2: Use Distance Formula
Distance = Speed × Time
When the cattle train catches up, both trains have traveled the
same distance from the station.
So:
$$
\text{Distance}_{\text{passenger}} = \text{Distance}_{\text{cattle}}
$$
$$
29.2 \times (t + 2.4) = 36.5 \times t
$$
---
Step 3: Solve the Equation
$$
29.2(t + 2.4) = 36.5t
$$
Expand the left side:
$$
29.2t + 29.2 \times 2.4 = 36.5t
$$
Calculate $ 29.2 \times 2.4 $:
$$
29.2 \times 2.4 = (29.2 \times 2) + (29.2 \times 0.4) = 58.4 + 11.68 = 70.08
$$
So:
$$
29.2t + 70.08 = 36.5t
$$
Subtract $ 29.2t $ from both sides:
$$
70.08 = 36.5t - 29.2t = 7.3t
$$
Now divide:
$$
t = \frac{70.08}{7.3}
$$
Calculate:
$$
t = 9.6 \text{ hours}
$$
---
Step 4: Find How Long the Passenger Train Traveled
The passenger train had a
2.4-hour head start, and the cattle train took
9.6 hours to catch up.
So, total time the passenger train traveled:
$$
t + 2.4 = 9.6 + 2.4 = 12 \text{ hours}
$$
---
✔ Final Answer:
$$
\boxed{12} \text{ hours}
$$
The passenger train traveled for
12 hours before the cattle train caught up.
---
🔍 Explanation:
Even though the cattle train is faster, it started later. The passenger train had a 2.4-hour head start, covering some distance first. The cattle train closes the gap at a rate of $ 36.5 - 29.2 = 7.3 $ km/h. The initial lead was $ 29.2 \times 2.4 = 70.08 $ km. At a closing speed of 7.3 km/h, it takes $ 70.08 / 7.3 = 9.6 $ hours for the cattle train to catch up. So the passenger train traveled $ 9.6 + 2.4 = 12 $ hours total.
Parent Tip: Review the logic above to help your child master the concept of distance equals rate times time worksheet.