You can find the slope either by just looking at the line or using the slope formula.
#1: The slope formula is:
Find two points and plug it into the formula
I will use (0, 2) and (1, -1)
(0, 2) = (x₁, y₁)
(1, -1) = (x₂, y₂)
[two negatives cancel each other out and become positive]
m = -3
#2: To find the slope without having to do the work, you use this:
Rise is the number of units you go up(+) or down(-) from each point
Run is the number of units you go to the right from each point
If we start at a defined/obvious point, like (0, 2), find the next point and see how many units it goes up or down and to the right. The next point is (1, -1), so from each point, you go down 3 units and to the right 1 unit. So your slope is -3/1 or -3. You can make sure the slope is right by looking at another point.
Answer: 6.93 years
Step-by-step explanation:
Given
Rate of interest is 
Future value is given by 
For the investment to double itself, i.e. 
It takes around 6.93 years to double the investment.
We have been given that the distribution of the number of daily requests is bell-shaped and has a mean of 38 and a standard deviation of 6. We are asked to find the approximate percentage of lightbulb replacement requests numbering between 38 and 56.
First of all, we will find z-score corresponding to 38 and 56.
Now we will find z-score corresponding to 56.
We know that according to Empirical rule approximately 68% data lies with-in standard deviation of mean, approximately 95% data lies within 2 standard deviation of mean and approximately 99.7% data lies within 3 standard deviation of mean that is 
.
We can see that data point 38 is at mean as it's z-score is 0 and z-score of 56 is 3. This means that 56 is 3 standard deviation above mean.
We know that mean is at center of normal distribution curve. So to find percentage of data points 3 SD above mean, we will divide 99.7% by 2.
Therefore, approximately 
of lightbulb replacement requests numbering between 38 and 56.
