Jennifer T.

asked • 06/04/14

A family is moving and has a number of electronic devices in the same packing crate. One of the devic

A family is moving and has a number of electronic devices in the same packing crate. One of the devices beeps every 8 minutes, another device beeps every 10 minutes, and a third device beeps every 12 minutes. If all the devices beeped together at 3:00 pm, what time will it be when they all beep together next?

1 Expert Answer

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Sarah F. answered • 06/04/14

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4.8 (6)

Patient Physics, Math, Chemistry, and ACT/SAT Tutor

Peter H.

Hi Jennifer,
 
The answer we have from Sarah is very good. In case you wonder - how do I find the Least Common Multiple - let me explain that part. First, we need to factor each of the three numbers (8, 10, 12). We need the prime factors; that is, factor the number down to its prime number components. We have -
 
   8 = 2 * 4 = 2 * 2 * 2
  10 = 2 * 5
  12 = 3 * 4 = 3 * 2 * 2
 
Next, we select the component prime numbers, starting with all of the components of the first number (8), and then the missing components from the others. So, we start with the 2 * 2 * 2 components of 8; from 10 = 2 * 5, we already have a 2, so we add the 5 component; from 12 = 3 * 2 * 2, we already have the two 2's, so we add the 3 component. In total, we have these components -
 
  2 * 2 * 2 * 5 * 3, which is 120
 
Our answer is therefore 120, just what Sarah gave us.
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06/04/14

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