Select the correct answer.
William recorded data to determine the relationship between the time usage, x, and the percentage of charge left on his mobile phone, y. He graphed the data and drew the line of best fit. The equation of the line of best fit is y = -10x + 100. About how many hours will it take for the phone lose its charge completely?
A.
about 5 hours
B.
about 10 hours
C.
about 20 hours
D.
about 22 hours
E.
about 24 hours
Since the equation is y = -10x + 100, when y (percentage of charge left) equals 0, we can solve for x (time usage):
0 = -10x + 100
10x = 100
x = 10
Therefore, it will take about 10 hours for the phone to lose its charge completely. The answer is B.
To determine the number of hours it will take for the phone to lose its charge completely, we can substitute y = 0 into the equation of the line of best fit and solve for x.
Given equation: y = -10x + 100
Substituting y = 0, we have:
0 = -10x + 100
Rearranging the equation:
10x = 100
Dividing both sides by 10:
x = 10
Therefore, it will take about 10 hours for the phone to lose its charge completely.
So, the correct answer is B. about 10 hours.
To determine the answer, we need to look at the equation of the line of best fit, which is y = -10x + 100. In this equation, y represents the percentage of charge left on the mobile phone, and x represents the time usage.
To find out how many hours it will take for the phone to lose its charge completely, we need to find the value of x when y is equal to 0 (since 0% charge means the phone has no charge left).
So, we can set y = 0 in the equation and solve for x:
0 = -10x + 100
Rearranging the equation, we get:
10x = 100
Dividing both sides by 10, we get:
x = 100/10
x = 10
Therefore, it will take approximately 10 hours for the phone to lose its charge completely.
The correct answer is B. about 10 hours.