Q&A - PSLE Math

[Muffins]

Tang:

tianzhu:

Thank you for your help.


How to show that the sum of all angles is equal to 360 degrees?
Q35 RGPS SA2 2007

http://www.wendykoh.com/07/primary6-rgs-maths.pdf

Partial c + d + f = 180 degree (triangle)

The other portion of c + b + a + e = 180 degree (triangle, External angle of a triangle = 2 internal opposite angles = a + e)

So all angles add up to 360 degree.

http://www.postimage.org/

[alamak]

[Moderator's note: Topics merged.]


Car A left Town X for Town Y at the same time when Car B left Town Y for Town X. The average speed of Car A was 56km/h and the average speed for Car B was 72km/h. The two cars passed each other at a point 24km from the midway of the two towns. What is the distance between Town X and Town Y? :?:

[alamak]

[Moderator's note: Topics merged.]


Mr Tan bought three times as many badges as toy cars and spent $144 in total. He spent $84 more on toy cars than on badges. Given that a toy car cost $10.40 more than a badge, what is the cost of a badge? :?

[alamak]

[Moderator's note: Topics merged.]


In a school science fair, there were exhibits from Primary 4 to Primary 6. Altogether 25 exhibits came from Primary 5 and 6. If 16 exhibits were not from Primary 6 and 15 exhibits were not from Primary 5, how many exhibits were there altogether?

[James Ang]

these days I am testing P6 students simple questions; such as what fraction is halfway between 1/32 and 1/2, what is the sum of angles for the vertices of a five-sided star and six-sided star, and how many tiles are arranged on 1 side if 60 tiles are used to form the perimeter of a square!

[finder]

Hi, please help. Thank you.


------------
Ning and Zhongwei jogged to and fro repeatedly along a straight path in a park between two points A and B. Ning jogged at a uniform speed of 4m/s and Zhongwei jogged at a uniform speed of 6m/s. They started jogging from opposite directions at the same time as show below,

A ------------------X-----------------------------------Y--------------------B

They first met one another at point X. The second time they met was at point Y.

a). Given that the distance between X and Y is 160 m. Find the distance between A and B.

b). If they started jogging at 8am, how long did they take to meet again for the third time? (Express your answers in minutes and seconds)

[oceandeep]

[Moderator's note: Topics merged.]


Gina, Hans, Ian and June bought a present for their mother. Gina paid 2/5 of what the rest paid. Hans paid 1/2 of what the rest paid. Ian paid 1/3 of what the rest paid. June paid $30 less than Ian. how much did the present cost?

[CMF]

Gina : 2 units

The rest : 5 units
Total : 7 units

Hans : 1 unit
The rest : 2 units
Total : 3 units

Ian : 1 unit
The rest : 3 units
Total : 4 units

Hence find the lowest common multiple of 3, 4 and 7 which is 84

As such :

Gina : 24 units
Hans : 28 units
Ian : 21 units

To find June’s share : Subtract (24 + 28 + 21) from 84 which gives 11 units.

Since June paid $30 less than Ian and the difference betw them is 10 units, 10 units therefore represents $30.

From the above, the total cost is $252 as the total number of units is 84
10 units : 10 x 3 = $30
84 units : 84 x 3 = $252

[Kari]

[Moderator's note: Topics merged.]


Lily is meeting a friend at a certain time.If she drives at 80km/hr, she will be 1/3 hour late. If she drives at 60km/hr, she will be 3/4 hour late. How long will the journey take if she drives at 90 km/hr?

[Eagle-Ladybird]

Kari:

Lily is meeting a friend at a certain time.If she drives at 80km/hr, she will be 1/3 hour late. If she drives at 60km/hr, she will be 3/4 hour late. How long will the journey take if she drives at 90 km/hr?

1 hr 11 minutes