Answer:The LCM of 10, 15, and 20 is 60. After 60 minutes, they ring together again.
Step-by-step explanation:
Answer:48 seconds per lap
Step-by-step explanation: 60 seconds per minute x 4 minutes= 240 seconds per lap. 240 seconds divided into 5 laps is 48 seconds per lap
Answer:
66
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