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0580/31 Oct/Nov 2021, Question 5: Mean, Median, Mode and Range

Cambridge IGCSE Mathematics 0580 · Paper 31 (Core) · Calculator · 5 marks

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The question, in short

From a table of 11 students' weekly hours on social media and television, work out spread, plot the remaining points, describe correlation, add a best-fit line and use it to estimate a value.

Summarised in our own words. Use the official paper for the exact wording and the diagram.

Part (a) · 1 mark

Work out the difference between the largest and smallest social media times in the table.

  1. 1Largest = 28, smallest = 2
  2. 2Range = 28 − 2 = 26 hours

Answer26

Part (bi) · 1 mark

Add the two remaining data pairs as crosses on the scatter diagram.

  1. 1The last two students are (19.5, 11) and (13, 20)
  2. 2Plot a cross at each point

AnswerPoints plotted at (19.5, 11) and (13, 20)

Part (bii) · 1 mark

State what kind of correlation the plotted points suggest.

  1. 1As social media time increases, television time decreases
  2. 2Negative correlation

AnswerNegative

Part (biii) · 1 mark

Add a straight line of best fit to the scatter diagram.

  1. 1Draw one ruled straight line with negative gradient through the middle of the points
  2. 2e.g. from about (2, 26) to (28, 10), with points balanced either side

AnswerCorrect ruled line

Part (biv) · 1 mark

Using 21 hours of television, read off from your line the estimated social media hours.

  1. 1Go across from Television = 21 to the line of best fit
  2. 2Read down to the social media axis: about 10 hours

Answer7.5 to 13.5

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