QUESTION:
A battery was charged. When the charging began, it was 23 percent full. After 30 minutes of charging, the battery was 89 percent full. how fast did the battery charge and how long did it take?
Solution :
<u>Given</u>
- Initial amount of charge = 23%
- Amount after charge = 89%
<u>procedu</u><u>re</u>
Let the rate of charging be r .
r = (change in charge level) / (time interval) = (89% - 23%) / (30 min) = 2.2 % per minute
charge = (rate of charging)(time) + (initial charge)
100% = r*t + 23%
100% = (2.2 %/min)t + 23%
Solve for t and get
t = [(100 - 23) / 2.2]
Answer = 35 min
Answer
Find out the the rate of the boat in still water.
To proof
let us assume that the speed of the boat in the still water = u
let us assume that the speed of the current = v
Formula
As given
18 miles downstream for 3 hours
Now for the downstream
u + v = 6
now for the upstream
As given
the trip back against the current takes 6 hours
u-v = 3
Than the two equation becomes
u + v = 6 and u - v = 3
add both the above equation
we get
2u = 9
u = 4.5miles per hour
put this in the u - v = 3
4.5 -v = 3
v =1.5 miles per hour
The rate of the boat in the still water is 4.5miles per hour .
Hence proved
Answer:
True
Step-by-step explanation:
70 bc the distance from b and c is 14 then multiply that by five cause that is the distance between c and d
I know you're using Khan Academy, anyway the answer is 135 mate.
