My son is named Sam and this is a pretty accurate account of what he's like before a trip.
Sam has an hour to charge things.
His tablet is at 40% and charges 12 points every 15 minutes. So four times that or 48 points in a hour. So after the hour his tablet is at 40+48=88%.
His phone went from 20% to 56% in 30 minutes, i.e. 36 points in 30 minutes. We can expect another 36 points for the remaining half hour, so after the hour his phone is at 56+36=92%
a. Answer: Tablet 88%, Phone 92%
b. To get a full charge on the tablet Sam needs to add 60 points at the rate of 12 points per 15 minutes, 60/12=5 15 minute intervals, which is 75 minutes.
To get a full charge on the phone, it starts at 20% so needs to get 80 points at the rate of 36 points per 30 minutes. So the total time is
(80/36)*30 = 200/3 minutes, which is 66 2/3 minutes.
Answer: Tablet: 75 minutes Phone: 66 2/3 minutes
