I believe the fastest way to solve this problem is to take any two of the given points and to find the slope and y-intercept of the line connecting those two points.
Let's choose the 2 given points (-3,16) and (-1,12).
Going from the first point to the second, the increase in x is 2 and the increase in y is actually a decrease: -4. Thus, the slope of the line connecting these two points is m = -4/2, or m = -2.
Now use the slope-intercept formula to find the y-intercept, b.
One point on the line is (-3,16), and the slope is m = -2.
Thus, the slope-intercept formula y = mx + b becomes 16 = -2(-3) + b.
Here, b comes out to 10.
So now we have the slope and the y-intercept. Write the equation:
y = mx + b becomes y=-2x+10. Which of the four given answer choices is the correct one?
⁴√400 / ⁴√5 = 400^¼ / 5^¼
= (5 x 2²)² / 5^¼
= 5² x 2⁴ / 5^¼
= ⁴√5^7 x 2⁴
121 is big enough to assume normality and not worry about the t distribution. By the 68-95-99.7 rule a 95% confidence interval includes plus or minus two standard deviations. So 95% of the cars will be in the mph range

The question is a bit vague, but it seems we're being asked for the 95% confidence interval on the average of 121 cars. The 121 is a hint of course.
The standard deviation of the average is in general the standard deviation of the individual samples divided by the square root of n:

So repeating our experiment of taking the average 121 cars over and over, we expect 95% of the averages to be in the mph range

That's probably the answer they're looking for.
Answer:
b. the area to the right of 2
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X, which is also the area to the left of Z. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X, which is the area to the right of Z.
In this problem:




Percentage who did better:
P(Z > 2), which is the area to the right of 2.
The answer to your question is positive