standard_description: Solve word problems involving addition and subtraction of fractions referring to the same whole, including cases of unlike denominators, e.g., by using visual fraction models or equations to represent the problem. Use benchmark fractions and number sense of fractions to estimate mentally and assess the reasonableness of answers. For example, recognize an incorrect result 2/5 + 1/2 = 3/7, by observing that 3/7 < 1/2.
problem_activity: Task
Jerry forgot to plug in his laptop before he went to bed. He wants to take the laptop to his friend's house with a full battery. The pictures below show screenshots of the battery charge indicator after he plugs in the computer.
[IMG]
When can Jerry expect that his laptop battery is fully charged?
At 9:27 AM Jerry makes a quick calculation:
The battery seems to be charging at a rate of 1 percentage point per minute. So the battery should be fully charged at 10:11 AM.
Explain Jerry's calculation.  Is his estimate most likely an under- or over-estimate? How does it compare to your prediction?
Compare the average rate of change of the battery charging function on the first given time interval and on the last given time interval. What does this tell you about how the battery is charging?
How long would it take for the battery to charge if it started out completely empty?


aligns: no