According to the manual, a battery in a cellular phone loses 2% of its charge each day assume the battery is 100% charged
a) Write an equation to represent the percent charge, P, as a function of the number of days, D, since the battery was charged.

b) Determine the number of days until the battery in only 50% charged.

Please show full solutions
Thanks

Question

According to the manual, a battery in a cellular phone loses 2% of its charge each day assume the battery is 100% charged 
a) Write an equation to represent the percent charge, P, as a function of the number of days, D, since the battery was charged.

b) Determine the number of days until the battery in only 50% charged.

Please show full solutions 
Thanks

anonymous · Answer

a:   p=100 - (2xD)
B: it would take 25 days to be at 50%

anonymous · Answer

can you please show me full work because i don't understand the question, thanks

anonymous · Answer

I think it's an exponential equation. Note it's discharging continuously.

anonymous · Answer

well in the equation p = 100 - (2D)        P is the battery left, and it equals 100% - 2% battery lost in each day. so if 2 days went by, it would be 96% battery left because 
96 = 100 - (2x2)

anonymous · Answer

I think its more like $$C=e ^{-.0202t}$$

Where t is the number of days and C is the percent of charge expresses a decimal.

So for a 50% charge,

 $$.5=e ^{-.0202t}$$

 t=34 days

anonymous · Answer

C is the percent of charge expressed as decimal.