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Scatter Graphs & Correlation Practice Questions

Question 1

3 marks

A garage sells second-hand cars of the same model. The table shows the age, in years, and the value, in £1000, of 8 of these cars.

Age (years) 1 2 3 4 5 6 7 8
Value (£1000) 12 11 9 9 7 6 5 3

The first 6 cars in the table have been plotted on the scatter graph below.

01234567802468101214Age (years)Value (£1000)

(a)

Complete the scatter graph by plotting the information for the last two cars in the table.

(b)

Write down the type of correlation shown by the scatter graph.

(c)

What does this type of correlation tell you about the value of these cars as they get older?

Question 2

3 marks

The scatter graph shows information about 12 pupils. It shows the number of hours of television each pupil watched in one week and the mark each pupil got in a test.

0246810121416182001020304050Hours of televisionTest mark

(a)

One of the points is an outlier.

Write down the coordinates of this point.

( .......................... , ..........................)

(b)

For all the other points, write down the type of correlation.

(c)

Sam says,

"The scatter graph shows that watching television causes pupils to get a lower test mark."

Comment on what Sam says.

Question 3

3 marks

For each pair of variables below, write down the type of correlation you would expect.

(a)

The number of people who visit a swimming pool in a day and the amount of money taken at the entrance desk that day.

(b)

The outside temperature and the number of bowls of hot soup sold in a café.

(c)

The length of a person's hair and the number of text messages they send in a week.