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A baby goes to sleep at 8 p.m., wakes up after two hours, stays awake for 15 minutes, and then goes back to sleep. If the baby repeats this sleep pattern until she is awakened at 6 a.m., what percent of the time from 8 p.m. to 6 a.m. was the baby asleep?

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 Sep 9, 2019
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We have 10 hours between  8PM  and 6AM  =   10 * 60  = 600 minutes

 

Sleep    8 -10

Awake  10 - 10:15

Sleep 10:15 - 12:15

Awake 12:15 - 12:30

Sleep 12:30 - 2:30

Awake 2:30 - 2:45

Sleep 2:45 - 4:45

Awake 4:45 - 5

Sleep  5 - 6

 

There are 4 periods of  2 hour sleep  and 1 period of 1 hour sleep  =  4*2(60) + 1(60)  =  480 + 60  = 540 minutes asleep

 

So      540/600   =  54/60   =  9/10   =   90%  of the time asleep

 

 

 

cool cool cool

 Sep 9, 2019
edited by CPhill  Sep 9, 2019

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