Problema Solution
Peter woke up at 8:00 am and realized he forgot to charge his cell phone. At 9:30 am, the battery had about 75% of a charge remaining. By 11:30 am, the battery was about 45% full. Assume that the battery is draining at a constant rate per hour. Write an equation for the amount of charge remaining in the battery in terms of the number of hours past 8:00 am. Show how you arrived at your equation. Show algebraically how you found the vertical intercept.
Answer provided by our tutors
(9:30, 75) and (11:30, 45).
So, slope is (45-75)/(11:30-9:30)= -30/2=-15
So, rate of draining is 15% per hour.
So, Equation is y=mx+b
at 9.30 am x=0.
So, 75=-15*0+b
b=75
Vertical intercept is 75.
So, equation is y=-15x+75.