GRADE SIX MATHEMATICS

Answers to Last Week’s Exercises

Revision Exercise: 1. (a) 27 (b) 2 510 000 2. (a) one thousand ninety-seven eight hundred seven thousand one hundred thirty-eight > (b) < (c) < 4. (a) (10 - 4) + 1 = 7 (b) 8 - (5 +2) = 1 (c) 2 + 9 – (3 + 4) = 4 (d) 14 – (6 + 1) – 5 = 2 7. 6 and 4 9. (a) Commutative (b) Identity (c) Distributive 10. 243 342 423 432 (b)

Exercise 1: 1. Even 2. Odd 3. Even. 4. Odd 5. Odd 6. Odd 7. Even. 8. Odd 9. Even 10. Even 11. 3 12. 2,4 13. None 14. 2,4 15. None 16. 2,3,4,9 17. 3,9 18. 3,9 19. 2,4 20. 2,3,4 21. (a)Yes (b) No. five million 3. (a) To find the average of a set of numbers or quantities do the following:►

ensure that all numbers or quantities are of the same unit ► find the sum of the numbers or quantities ► divide the result by the number of numbers in the set.

Study this example: (i) Find the average of 78, 32, 0 and 14.

The numbers have no units. The sum (78 + 32 + 0 + 14) = 124 The number of numbers in the set = 4 Average = 124 ÷ 4

= 31

Exercise 2 Complete these

1. In five days a Peter had the following attendances 28, 30, 27, 25 and 10. What was the average attendance?

2. On a journey lasting 3 hours a motor car travels 45km in the first hour, 50 km in the second hour and 40 km in the third hour. What is the average speed per hour?

3. Three parcels weigh 38kg, 34kg and 33kg. What is the average weight of the parcels?

4. Kathy’s dad bought his children some toys. The bicycle cost $4 000, a toy car for $1 500 and a doll for $2 000. Calculate the average cost for a toy?

5. Find the average of 3 metres and 50 centimetres. Study this:

(ii) The average of 4 numbers is 40. If two of the numbers are 57 and 65. What is the fourth number? Average of 4 numbers = 40 Sum of 4 nos. = 40 x 4 = 160 = 122 = 160 – 122 = 38 (iv) The average of 3 numbers is 35. If the average of 2 of them is 50. What is the third number? Sum of 57 and 65 Third number

Average of 3 numbers is 35 Total of three numbers = 35 x 3 = 105 Average of 2 numbers is 50 Total of 2 numbers = 50 x 2 = 100 = 105 - 100 = 5 The third number

AVERAGE

Exercise 3 1. The average of 38 and 7 is equal to the average of 15 and ______.

2. June bought 3 books @ $2.45 each and 2 books @ $3.85 each. What was the average cost per book?

3. If the average of three numbers is 23, and the average of 2 of them is 25, then the third number is __________ .

4. The average of three numbers is 90. If two of them are 88 and 64, what is the third number?

5. The average of 4 numbers is 43. If three of the numbers are 43, 36 and 24. What is the fourth number?

6. The average of 3 numbers is 70. What will be the average after 25 and 15 are added to these numbers?

7. The average of 5 numbers is 60. The average of the first two of these numbers is 21, find the average of the other 3 numbers.

Do enjoy your week at school. Remember to share this article with someone. Goodbye boys and girls.