Answer:
a. The phone will be at 92% and the tablet will be at 88%
b. One hour and 15 minutes for both devices to finish charging.
Step-by-step explanation:
For Part A), we can find that Sam's phone battery is increasing by 12% every 10 minutes. By multiplying 12 by 3 (30 minutes) and adding it to the 56% from the first 30 minutes, we get the answer 92%. The tablet charges 12% per every 15 minutes, and one hour has four sets of 15 minutes. So 12 times 4 and then added to 40% gives us 88%.
For Part B), we must calculate how much time it takes before both devices are fully charged. Because it charges at a slower rate and will finish last, we must rely on the rate of the tablet for this question. At a rate of 12% per 15 minutes, Sam's devices would both be fully charged after an hour and 15 minutes. This is because an additional 15 minutes would give the tablet 12% more battery, and 88 + 12 = 100. If you also needed to know when the phone would finish charging by itself, you would find that the phone only needed 8% left to become 100%. The phone charges at 12% per 10 minutes, and 8 is 2/3 of 12. This would mean the phone would need roughly an additional 7 minutes to charge, making for a total of one hour and 7 minutes for the phone.
Hope this helps!
