Challenging P5 2009 SA1 P2 MGS Q17

17. The following figures are made up of 2-cm squares.

a) What is the perimeter of Figure 3?

b) How many squares are there in Figure 6?

c) Which figure has an area of 220 cm²?

By moving all sides out, we get a big square.

3 x 4 = 12

12 x 2 = 24 cm

a) The perimeter of Figure 3 is 24 cm.

1

1 + 2

1 + 2 + 3

..

1 + 2 + 3 + 4 + 5 + 6 = 21 squares

b) There are 21 squares in Figure 6.

2 x 2 = 4

220 ÷ 4 = 55 squares

21 + 7 = 28

28 + 8 = 36

36 + 9 = 45

45 + 10 = 55 -- > Figure 10

c) Figure 10 has an area of 220 cm².

Challenging P5 2009 SA1 P1 MGS Q13

13. The picture below shows a dart board. Benny threw 3 darts and all the 3 darts hit the board. Which of the following is NOT likely to be his score?

(1)  75

(2)  80

(3)  125

(4)  135

Tabulate out the possible numbers to help you to see and calculate the total.

1st dart  2nd dart  3rd dart

--------------------------------

  5                5                5

 25              25              25

 50              50              50

100            100            100             

25 + 25 + 25 = 75 √

5 + 25 + 50 = 80 √

25 + 50 + 50 = 125 √

So 135 is NOT a likely score and the answer (4).