题目

Nikki usually leaves her cell phone on.If her cell phone is on but she is not actually using it,the battery will last for 24 hours.If she is using it constantly,the battery will last for only 3 hours.Since the last recharge,her phone has been on 9 hours,and during that time she has used it for 60 minutes.If she doesn’t talk any more but leaves the phone on,how many more hours will the battery last?

提问时间：2020-10-30

答案

电话待机状态,电池可用24小时,如果持续使用,电池只能用3小时.如果刚充完电,开机了9小时,并且在这9小时中使用了60分钟,如果不再通话,可再待机多久?
答案：还可以再待机7小时,
设电量为1,待机每小时的用电量为1/24,通话每小时的用电量为1/3
后来这次 先待机9h,用电量为 1/24 * 9,然后通话 60分钟=1h,用电量为 1*1/3
用剩余的电量 1- 9/24- 1/3 除以待机每小时的用电量 1/24,结果为 7h.