Let’s solve the first problem step by step.
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Problem 1:
Jill jogged at an average speed of 12 km/h from her home to the nearby park and jogged back at an average speed of 4 km/h via the same route. If she took a total time of 57 min, how long did she take to jog from her home to the nearby park?
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Step 1: Understand what we know
- Speed going to park = 12 km/h
- Speed returning home = 4 km/h
- Total time for round trip = 57 minutes
- Distance to park = distance back (same route)
- We need to find: time taken to go TO the park (in minutes)
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Step 2: Convert total time to hours (since speeds are in km/h)
57 minutes = 57 ÷ 60 = 0.95 hours
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Step 3: Let distance to park be D km
Then:
- Time to park = D / 12 hours
- Time back home = D / 4 hours
Total time = D/12 + D/4 = 0.95 hours
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Step 4: Solve the equation
D/12 + D/4 = 0.95
Find common denominator — 12
→ D/12 + 3D/12 = 0.95
→ 4D/12 = 0.95
→ D/3 = 0.95
→ D = 0.95 × 3 = 2.85 km
So, distance to park is 2.85 km.
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Step 5: Find time to park
Time = Distance ÷ Speed = 2.85 ÷ 12 = 0.2375 hours
Convert to minutes: 0.2375 × 60 = 14.25 minutes
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Step 6: Check answer
Time back = 2.85 ÷ 4 = 0.7125 hours → 0.7125 × 60 = 42.75 minutes
Total time = 14.25 + 42.75 = 57 minutes
✔ Correct!
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Final Answer:
14.25
Parent Tip: Review the logic above to help your child master the concept of singapore maths worksheet.
