Three friends ride bicycles around a circular track in Singapore. Mei Ling completes one lap every 3 minutes, Stan completes one lap every 4 minutes, and Sara completes one lap every 6 minutes. They all start together at the start line. After how many minutes will they ALL be at the start line together for the FIRST time after starting?
Show Worked Solution
Worked Solution
Step 1: Each friend is at the start line at multiples of their lap time. Mei Ling: 3, 6, 9, 12, 15, … Stan: 4, 8, 12, 16, … Sara: 6, 12, 18, …
Step 2: The first number that appears in ALL three lists is 12.
Step 3: So they meet at the start line for the first time after 12 minutes.
Answer: 12 minutes
Correct answer: 12 minutes
Want more questions like this? Superholic Lab has 10,000+ MOE-aligned questions with full worked solutions.
Start Free Trial — 7 Days Free