Problem Solving Unit

Year 9 Interactive Maths - Second Edition

Problem 17.1 The Average
1.	The average of five numbers is 7. A sixth number is added and the new average is 8. Find the sixth number.
2.	The average weight of 2 girls is 41 kg and the average weight of 3 boys is 51 kg. Determine the average weight of the 5 children.
3.	A batsman's average over five innings is 32 runs. What is the total number of runs made by the batsman?
4.	A batsman's average over n innings is y runs. What is the total number of runs made by the batsman?
5.	A basketball player's average score over 6 games is 30 points. Determine her average after the next game, in which she scores 65 points.
6.	A basketball player's average score over n games is a points. Find an expression for her average after the next game, in which she scores b points.
Problem 17.2 How Far? A farmer drives from one farm to another averaging 70 kilometres per hour. On the return trip he averages 60 kilometres per hour and it takes 50 minutes longer. How far apart are the two farms?

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