Higher November 2021 Paper 5 Q4

OCRHigherCurrent spec8 marksScatter Diagrams & Correlation

4 The table shows the marks obtained by 10 students in spelling tests in January and February.

Mark in January26535048306670443738
Mark in February42586858668286604850

The marks for the first six students are plotted on the scatter diagram.

Scatter diagram with Mark in January from 20 to 80 on the horizontal axis and Mark in February from 20 to 90 on the vertical axis, with the first six students plotted as crosses
(a) Plot the marks for the remaining four students. [2]
(b) Describe the type of correlation shown in the completed scatter diagram. [1]
(c)
(i) On the scatter diagram, circle the student that made the greatest improvement in their marks from January to February. [1]
(ii) Work out the percentage change in this student’s marks from January to February. [3]
(d) Another student, Kai, scored 79 marks in the test in January but was absent for the test in February.

Kai says

I could use a line of best fit on the scatter diagram to estimate the marks I may have achieved in the test in February.

Is Kai’s method reliable?
Give a reason for your answer. [1]

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