Answer:
a) (1215, 1297)
b) (1174, 1338)
c) (1133, 1379)
Step-by-step explanation:
We are given the following information in the question:
Mean, μ = 1256
Standard Deviation, σ = 41
Empirical Rule:
- Also known as 68-95-99.7 rule.
- It states that almost all the data lies within three standard deviation for a normal data.
- About 68% of data lies within 1 standard deviation of mean.
- About 95% of data lies within two standard deviation of mean.
- About 99.7% of data lies within 3 standard deviation of mean.
a) range of years centered about the mean in which about 68% of the data lies

68% of data will be found between 1215 years and 1297 years.
b) range of years centered about the mean in which about 95% of the data lies

95% of data will be found between 1174 years and 1338 years.
c) range of years centered about the mean in which about all of the data lies

All of data will be found between 1133 years and 1379 years.
We use the trigonometric function for this case. An escalator is an inclined path. We form a right triangle since we have given the value of the height. The height from the first floor to second floor is called the adjacent while the travelled distance of the people is called the hypothenuse. We use cosine function because we are given in terms of adjacent and hypothenuse. The ratio of cosine function is
cos x = a/h
where x is the angle
Solving for h,
h = a/(cos x) = 21/(cos 30) = 24.25 ft
2y - 18x = -26
Add 18x to both sides.
2y = -26 + 18x
Divide by 2 on both sides.
y = -13 + 9x
y = 9x - 13
X=2/3y-4
EXPLANATION
3x-2y=-12
You take -2y to the other side
It becomes 3x=2y-12
Then you divide 3
X=2/3y
-12/3=-4
X=2/3y-4