Respuesta :
Answer:
6 hrs
Step-by-step explanation:
Given:-
- The current battery, xi = 2/5
- The drain rate, r = 1/9 per hour
Find:-
how many hours will the battery last
Solution:-
- The battery after every (nth) hour would be (an) with initial value of (xi) at a rate of (r). A geometric sequence can be developed:
an = xi*r^(n-1)
- Hence,
an = (2/5)*(1/9)^( n - 1 )
- When Vera is out of battery, an = 0:
0 = (2/5)*(1/9)^( n - 1 )
- We will use an approximation for 0% battery upto 5 decimal places:
n = 6
an = 0.00000677404
