Question

Mark charged a battery. Each minute, the percentage of the battery's capacity that was charged increased by 2.52.52, point, 5 percent. After 171717 minutes of charging, the battery was 61.561.561, point, 5 percent full. How full was the battery when the charging began?

Answer 1

1.)19 %

2.)32.4 minutes to be fully charged

i just did it on khan

Answer 2

19%.

Explanation:

We have been given that Mark charged a battery. Each minute, the percentage of the battery's capacity that was charged increased by 2.5%. After 17 minutes of charging, the battery was 61.5% full.

We will use slope-intercept form of equation to solve our given problem. We know that the equation of a line in slope-intercept form is:
`y=mx+b`, where,

m = Slope of line,

b = The y-intercept or initial value.

Since battery is charged 2.5% per minute, so slope of line would be 2.5.

We are also told that after 17 minutes of charging, the battery was 61.5% full. Now, we will use point
`(17,61.5)` to solve for initial value or b as:

`61.5=2.5\cdot 17+b`

`61.5=42.5+b`

`61.5-42.5=42.5-42.5+b`

`19=b`

Therefore, the battery was 19% full, when the charging began.