A remote control car can run for one hour at normal speed, 40 minutes at turbo speed, and 20 minutes at hyperturbo speed before its battery life is consumed. After running for 2 minutes at hyperturbo speed and 18 minutes at turbo speed, how much longer can the car run at normal speed, assuming it started with a fully charged battery?

Guest Jun 11, 2022

#1**+1 **

After running for 2 minutes at hyperturbo speed, the battery has

1 - 2/20 = 1 - 1/10 = .9 of its battery life left

And after running for another 18 minutes at turbo speed, the battery has

.9 - 18/40 = .9 - 9/20 = .9 - .45 = .45 of its battery life left

So....after switching to normal speed

The car can run for 60 * .45 = 27 more minutes

CPhill Jun 11, 2022