Question

A rechargeable battery in a laptop computer is regularly used over a 24 hour period with the
following units consumed. However, the battery only has a charge of 4 units at the beginning of
today. The battery will be continually charging at a rate of 1/2 unit per hour. You can assume that
the consumption of units is uniform within each 8 hour period.
Time period Total units used during the period
00:00 – 08:00 4
08:00 – 16:00 8
16:00 – 24:00 4
When does the battery completely run out of charge?
A 04:00
B 08:00
C 12:00
D 16:00
E 24:00

Answer 1

how much charge does it have at 08:00?

Answer 2

00:00-08:00=4 units
08:00-16:00=8units
16:00-24:00=4 units

Answer 3

no, that tells you how much is used in total units between 0:00 and 8:00, not how full the battery is

Answer 4

to find the charge at 01:00, you need to take away any charge used, and add any charge recharged. For example the battery consumes 4/8 = 1/2 during each of the first 8 hours, and also replenishes 1/2 during each of the first 8 hours. But during 08:00 to 16:00 it uses up more charge.

Answer 5

ok thank you