Data and charts · Ages 11–12

The mean (average) worksheet

Part of: Line graphs, the mean (average) and pie charts

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Data and charts · Ages 11–12

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Name:Date:Score:／48

Write each answer in the space. For word problems, show your working and write a sentence answer.

13.The mean height of 6 pupils is 135 cm. A pupil 142 cm tall joins them. What is the group's mean height now, in centimetres?
Working:
Answer:
14.Ka-lok and 3 friends have lunch together, and the bill comes to $240. If Ka-lok and the friends share it equally, how many dollars does each person pay?
Working:
Answer:
15.The mean of three numbers is 31. Two of them are 29 and 51. What is the third?
Working:
Answer:
16.Ka-yee buys match tickets for 4 friends, paying $468 in all, and isn't going herself. If the friends pay Ka-yee back equally, how many dollars does each friend pay?
Working:
Answer:
17.Chi-keung and 4 friends have lunch together, and the bill comes to $375. If Chi-keung and the friends share it equally, how many dollars does each person pay?
Working:
Answer:
18.The mean of three numbers is 72. Two of them are 75 and 32. What is the third?
Working:
Answer:

Show the answers and working

The mean (average) worksheet: Answers and working

1. Mean of 41, 44, 53 is 46
The total must be mean × how many, then take the numbers given: 46 × 3 = 138, 138 − 41 = 97, 97 − 44 = 53
2. Mean of 51, 50, 31 = 44
Mean = total ÷ how many: 51 + 50 = 101, 101 + 31 = 132, 132 ÷ 3 = 44
3. Mean of 44, 27, 25 = 32
Mean = total ÷ how many: 44 + 27 = 71, 71 + 25 = 96, 96 ÷ 3 = 32
4. Mean of the skips = 50
Mean = total ÷ how many: 45 + 46 = 91, 91 + 53 = 144, 144 + 56 = 200, 200 ÷ 4 = 50
5. Mean of the buns = 32
Mean = total ÷ how many: 36 + 37 = 73, 73 + 20 = 93, 93 + 35 = 128, 128 ÷ 4 = 32
6. Mean of 35, 36, 25 = 32
Mean = total ÷ how many: 35 + 36 = 71, 71 + 25 = 96, 96 ÷ 3 = 32
7. Mean of the buns = 21
Mean = total ÷ how many: 13 + 16 = 29, 29 + 29 = 58, 58 + 26 = 84, 84 ÷ 4 = 21
8. Mean of the books = 16
Mean = total ÷ how many: 14 + 6 = 20, 20 + 18 = 38, 38 + 26 = 64, 64 ÷ 4 = 16
9. Mean of 17, 3, 10 = 10
Mean = total ÷ how many: 17 + 3 = 20, 20 + 10 = 30, 30 ÷ 3 = 10
10. Mean of the buns = 52
Mean = total ÷ how many: 48 + 53 = 101, 101 + 60 = 161, 161 + 47 = 208, 208 ÷ 4 = 52
11. Mean of 39, 55, 59 is 51
The total must be mean × how many, then take the numbers given: 51 × 3 = 153, 153 − 39 = 114, 114 − 55 = 59
12. Mean of the skips = 17
Mean = total ÷ how many: 29 + 18 = 47, 47 + 9 = 56, 56 + 12 = 68, 68 ÷ 4 = 17

Marking: 2 for the working, 1 for the answer, 1 for the sentence.

13. The mean height of 6 pupils is 135 cm. A pupil 142 cm tall joins them. What is the group's mean height now, in centimetres? (Answer: 136 cm)
6 × 135 = 810; 6 × 135 + 142 = 952; (6 × 135 + 142) ÷ (6 + 1) = 136
14. Ka-lok and 3 friends have lunch together, and the bill comes to $240. If Ka-lok and the friends share it equally, how many dollars does each person pay? (Answer: 60 dollars)
Ka-lok pays too: 3 + 1 = 4 people, so 240 ÷ 4 = $60
15. The mean of three numbers is 31. Two of them are 29 and 51. What is the third? (Answer: 13)
3 × 31 = 93; 3 × 31 − 29 − 51 = 13
16. Ka-yee buys match tickets for 4 friends, paying $468 in all, and isn't going herself. If the friends pay Ka-yee back equally, how many dollars does each friend pay? (Answer: 117 dollars)
The tickets are only for the 4 friends, so Ka-yee pays no share: 468 ÷ 4 = $117
17. Chi-keung and 4 friends have lunch together, and the bill comes to $375. If Chi-keung and the friends share it equally, how many dollars does each person pay? (Answer: 75 dollars)
Chi-keung pays too: 4 + 1 = 5 people, so 375 ÷ 5 = $75
18. The mean of three numbers is 72. Two of them are 75 and 32. What is the third? (Answer: 109)
3 × 72 = 216; 3 × 72 − 75 − 32 = 109

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