Respuesta :
Answer:
20, 40, 60
Step-by-step explanation:
We can find the LCM by making a list which is my favorite way.
Cell phone number 1: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60
Cell phone number 2: 5, 10, 15, 20, 25, 30, 35 40, 45, 50, 55, 60
Answer:
The first three times that the cell phones beep at the same time are the 20th, 40th and 60th minutes.
Step-by-step explanation:
Let the first cell phone be A, that is, A beeps every 4 minutes
and let the other cell phone be B, that is, B beeps every 5 minutes.
Cell phone A will be at the 4th, 8th, 12th, 16th and 20th minutes while cell phone B will beep at the 5th, 10th, 15th and 20th minutes. Hence, the first time the cell phones will beep together is the 20th minute.
Cell phone A will then beep at the 24th, 28th, 32nd, 36th and 40th minutes while cell phone B will beep at the 25th, 30th, 35th and 40th minutes. The second time the cell phones will beep together is the 40th minute.
Cell phone A will beep at the 44th, 48th, 52nd, 56th and 60th minutes while cell phone B will beep at the 45th, 50th, 55th and 60th minutes. The third time the cell phones will beep together is the 60th minute.
Hence, the first three times that the cell phones beep at the same time are the 20th, 40th and 60th minutes.
