2004 AMC 8 Problems/Problem 12
Problem
Niki usually leaves her cell phone on. If her cell phone is on but
she is not actually using it, the battery will last for 
hours. If
she is using it constantly, the battery will last for only 
hours.
Since the last recharge, her phone has been on 
hours, and during
that time she has used it for 
minutes. If she doesn’t use it any
more but leaves the phone on, how many more hours will the battery last?
Solution
When not being used, the cell phone uses up 
of its battery per hour. When being used, the cell phone uses up 
of its battery per hour. Since Niki's phone has been on for hours, of those 
simply on and 
with Niki using her phone, 
of its battery has been used up. To drain the remaining the phone can last for 
more hours without being used.
See Also
| 2004 AMC 8 (Problems • Answer Key • Resources) | ||
| Preceded by Problem 11 |
Followed by Problem 13 | |
| 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | ||
| All AJHSME/AMC 8 Problems and Solutions | ||
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. 
