Question

According to the manual, a battery in a cellular phone loses 2% of its charge eachday. Assume the battery is 100% charged. Write an equation to represent thepercent charge, P, as a function of the number of days, d, since the battery wascharged and use it to determine the number of days until the battery in only 50%charged.

Answer 1

a.) According to the manual, a battery in a cellular phone loses 2% of its charge each

day.

b.) Assume the battery is 100% charged.

Let,

P = the percent charge

d = the number of days since the battery was charged

The equation will be:

P = 100 - 2d

Let's determine the number of days until the battery in only 50% charged.

P = 100 - 2d

50 = 100 - 2d

2d = 100 - 50

2d = 50

2d/2 = 50/2

d = 25

Therefore, the battey will be only 50% charged in 25 days.