Answer:
The answer is y=-x+9.
The first thing to do is find where the line intercepts the y-axis, which is at positive 9 so you'll add a +9 to the end of your equation. Next you find the slope and since it's going down left to right, you know it is a negative. Now slope is found by change in y divided by change in x. And since both change and y and change in x are both 1, 1/1 is 1. And since you know it's negative that means the slope is -x. Altogether you get y= -x+9
The mean = 2,000
s = Sigma ( standard deviation ) = 300
M - 2 s = 2,000- 2 * 300 = 2,000 - 600 = 1,400
M + 2 s = 2,000 + 2 * 300 = 2,000 + 600 = 2,600
Answer.
Useful life of light bulbs within 2 standard deviations of the mean is:
A ) Between 1,400 and 2,600 hours