A8. Data on the numbers of hours of attendance per week and exam results for a c

Question

A8. Data on the numbers of hours of attendance per week and exam results for a class of 20 students was collected. A scatter diagram of these two variables is presented in Figure A3.1 Examine the scatter diagram and answer questions and (ii). Figure A3.1+ Exam results E0 Hours of Attendance i) Describe the relationship between the number of hours of attendance per week and exam results, identifying the dependent and independent variables.*' ii) Write down an expression for the linear regression equation to predict the variation in exam results from attendance.

Explanation / Answer

1) Although relationship is not compltely linear, it is a positive relationship

Exam results get better as the attendance hours increase.

Dependent variable = exam results

InDependent variable = Hours of attendance

b) Let's take 2 points

x = 4, y = 40

40 = 4m + c

x = 13, y = 80

80 = 13m + c

Subtract both we get:

9m = 40

m = 4.44

So

80 = 13 * 4.44 + c

c = 22.28

Equation:

y = 4.44 * x + 22.28

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