Tao Nan School P5 SA2 2006 Math Q43

A container measuring 17cm by 8cm by 10cm was half filled with water. When 8 cubes were put in, the water level became 8cm. Find the volume of each cube.

Solution

Height increase -----
8 cm (new height) – 5 cm (half tank) = 3 cm

Volume of 8 cubes -----
17cm x 8cm x 3cm
= 408 cubic cm

1 cube ----- 408 cubic cm divided by 8
= 51 cubic cm

Answer: 51 cubic cm

Tao Nan School P5 SA2 2006 Math Q42

Alex has some red pens and blue pens in the ratio of 7:3. He has 20 more red pens than blue pens. What is the new ratio of the number of red pens to the number of blue pens after he has given away 5 blue pens?

Solution

Red : Blue
7 : 3
Difference between blue and red -----
4 units ----- 20
1 unit ----- 5

Number of pens
Red ----- 7 x 5 = 35
Blue ----- 3 x 5 = 15

After 5 blue pens given away
Red ----- 35
Blue ----- 15 – 5 = 10

New ratio
Red : Blue
35 : 10
7 : 2

Answer: The new ratio of red pens to blue pens is 7:2

Tao Nan School P5 SA2 2006 Math Q41

Faridah, Iman and Erin shared some money in the ratio of 8:5:3. Iman and Erin had a total of $48. How much more money did Faridah have than Iman?

Solution

Faridah : Iman : Erin
8 : 5 : 3

Iman and Erin -----
8 units ----- $48
1 unit ----- $48 divided by 8 = $6

Faridah more than Iman -----
3 units ----- 3 x $6 = $18

Answer: Faridah had $18 more than Iman.

Tao Nan School P5 SA2 2006 Math Q40

Joe had $68 more than Mark. Bobbi had thrice as much as Mark. On the average, each person had $56. How much money did Joe have?

Solution




* Average per person is $56. Total amount is -----
3 x $56 = $168

5 units ----- $168 - $68 = $100
1 unit ----- $100 divided by 5 = $20

(Joe) 1 unit + $68 ----- $20 + $68 = $88

Answer: Joe had $88

Tao Nan School P5 SA2 2006 Math Q39

An orange cost ½ as much as a watermelon. Jiamin paid $21 for 12 watermelons and 6 oranges. How much did she pay for the 6 oranges?

Solution

Orange ----- 1 unit
Water Melon ----- 2 units

12 water melons + 6 oranges ----- $21
(12 x 2 units) + 6 units ----- $21
24 units + 6 units ----- $21
30 units ----- $21
1 unit ------ $21 divided by 30 = $0.70

(6 oranges) 6 units ----- 6 x $0.70 = $4.20

Answer: She paid $4.20

Tao Nan School P5 SA2 2006 Math Q38

A shopkeeper bought 280 apples. 28 of them were rotten. He then sold 63 of the good ones to Seng and the rest to Ming. What fraction of the good apples did Ming buy? (Give your answer in the simplest form)

Solution

280 (apples) – 28 (rotten) = 252 (good apples)

252 – 63 = 189 (apples sold to Ming)

Fraction Ming bought ---- 189/252 = ¾

Answer: Ming bought ¾ of the apples.

Hormat Senjata in 2 moves

Our son completed his BMT today and what a difference NSF is today compared to what it was years ago.

For those who have done NS in the early days when the AR-15 (assault weapon) was in use, you’ll be amazed at how quick the hormat senjata can now be done - in just 2 moves – all because the clumsy AR-15 has been replaced by a shorter weapon.

Watch this video how clean and neat the hormat senjata is done – as compared to the old way.


Take note (picture below) that even in senang diri position (note the feet apart), the weapon is still slung over the shoulder – unlike the AR-15 that has to be put on the ground. This means that the soldiers can now hormat senjata from sedia position, and not from sedia, then rusuk senjata, then hormat senjata.

How things have changed.

Tao Nan School P5 SA2 2006 Math Q37

If Elicia buys 2 kg of squids, she will have $28.90 left. If she buys 5 kg of squids, she will have $10.60 left. How much money does Elicia have?

Solution


3 units ----- $28.90 - $10.60 = $18.30
1 unit ----- $18.30 divided by 3 = $6.10

Elicia has
5 units + $10.60
= 5 x $6.10 + $10.60
= $41.10

Answer: She has $41.10

Tao Nan School P5 SA2 2006 Math Q36

Mary collected 75 sticks and Rose collected 43. After giving 22 sticks to their younger sister, they put the remainder equally into 4 boxes. How many sticks were there in each box?

Solution

Total collected ----- 75 + 43 = 118
Gave to sister ----- 118 – 22 = 96
96 (sticks) divided 4 (boxes) = 24

Answer: There were 24 sticks in each box.

Calculating the Area of a Triangle

Area of a triangle = ½ x base x height

A very common mistake students make is extending the base outside the triangle.
Example -
Question – Find the area of the shaded triangle.


Common Mistake (Wrong solution)

A common mistake students make in the above question is:-

Area of triangle = ½ x base x height
= ½ x 6cm x 3cm = 9 square cm (wrong)

The base should be 4 cm and not 6 cm. The question asks you to calculate the area of the SHADED triangle. The base of the shaded triangle is 4 cm.

If you put the base as 6 cm, you will calculate the area of the WHOLE figure as shown below.



The correct answer is as follows:

Area of triangle = ½ x base x height
= ½ x 4cm x 3cm = 6 square cm (correct answer)

In order to avoid making the mistake above, always remember that the base of the triangle must never extend outside the triangle.