Question

6. How would driving speed relate to fuel efficiency? A study on driving speed (miles per hour) and fuel efficiency (miles per gallon) resulted in the following sample data for sedans:

Driving Speed 30 50 40 55 30 25 60 25 50 55

Fuel Efficiency 28 25 25 23 30 32 21 35 26 25

a. Construct a scatter plot with driving speed on the horizontal axis and fuel efficiency on the vertical axis

b. Calculate the mean, median, variance, and standard deviation for each variable.

c. Judging from the scatter plot, comment on the relationship between the two variables.

d. Calculate the correlation between the two variables. Are they strongly related?

Answer 1

Using excel to show the working.

a)

b)

b

C) By observing the scatter plot we see that driving speed and fuel effeciency os negatively correlated. When one goes down the other increases.

d) Using the correl funtion , I found out the correlation of both the variable in excel. It came up to be -.910369. This means they have a strong correlation which is negatively.

A number which is inclined towards -1 shows that they are negatively correlated.