Q&A - PSLE Math

[Uncle Joe]

Uncle Joe:

abc_parent:

Hi gurus,

I have some questions from various papers 1.

NanHua SA1 2009

Q14) Adrian and Bob started driving at the same time. Bob took 6 hours to complete his journey while Adrian took 9 hours to complete his. After 3 hours ,the two men were left with the same distance to complete. What is the ratio of the distance of Bob's journey to the distance of Adrian's journey?

Ans: 4:3


Nan Hua Prelims 2009

Q14) Which one of the following shapes does not tessellate? -> I don't have picture so please help if you can.

Ans: (4) is the given answer correct?

Catholic High Prelims 2009

Q30) A man travels from Town X to Town Y at 4km/h and from Town Y to Town X at 6 km/h via the same route. The whole journey takes 45 minutes. Find the distance from Town X to Town Y.

Ans: 1.8km (how? I got 3.8km)
I got 1.8Km
speed:
4:6
2:3
Time:
3:2
so take 45min divide by (3+2) then multyply by 3 or 2.
the rest go and think about it
SCGS Prelims 2009

Q15) Alan completed a race in 1h 40 min. In the race, the ran at an average spped of 30m/min from Point A to Point B and then ran back from Point B to Point A at an average speed of 20m/min. How long did he take to run back to Point A from Point B?

Ans: I don't have it. Choices of 40 min, 50 min, 60 min, 100 min.
I think is 60 min
Nanyang Prelims 2009

Q15)This question has a diagram. Please help if you have the exam paper.
The 4 containers below each contains the same amount of water with different number of objects. What is the volume of object Y?

Ans: Given answer is 80 cubic cm.

[tianzhu]

Hi


Hope this helps.

Best wishes
http://farm5.static.flickr.com/4145/5021606703_880283ffe4_z.jpg\">

[Yu Xuan]

Uncle Joe:

Uncle Joe:

[quote=\"abc_parent\"]Hi gurus,

I have some questions from various papers 1.

Catholic High Prelims 2009

Q30) A man travels from Town X to Town Y at 4km/h and from Town Y to Town X at 6 km/h via the same route. The whole journey takes 45 minutes. Find the distance from Town X to Town Y.

Ans: 1.8km (how? I got 3.8km)
I got 1.8Km
speed:
4:6
2:3
Time:
3:2
so take 45min divide by (3+2) then multyply by 3 or 2.
the rest go and think about it
SCGS Prelims 2009

.

[/quote]Speed ratio
XY : YX --> 4 : 6 --> 2 : 3

Time Ratio
XY : YX --> 3 : 2

Total time --> 3units + 2 units = 5units
5units --> 45/60 h
3units --> 45/60 * 3 /5 = 9/20h

Distance --> 9/20h * 4km/h = 1 4/5km

[Yu Xuan]

Uncle Joe:

Uncle Joe:

[quote=\"abc_parent\"]
[Nan Hua Prelims 2009

Q14) Which one of the following shapes does not tessellate? -> I don't have picture so please help if you can.

Ans: (4) is the given answer correct?

[.

[/quote]Yes 4 is the answer.

[Yu Xuan]

Uncle Joe:

Uncle Joe:

[quote=\"abc_parent\"] Nanyang Prelims 2009


Q15)This question has a diagram. Please help if you have the exam paper.
The 4 containers below each contains the same amount of water with different number of objects. What is the volume of object Y?

Ans: Given answer is 80 cubic cm.

[/quote]Comparing the bottom 2 containers;
1X + 1Y = 380 - 240 = 140

Comparing the top right and bottom left containers;
3X = 380 - 200 = 180
1X = 180 / 3 = 60

Hence;
1Y --> 140 - 60= 80

[firebird]

Dear all


Good afternoon.

Please help me on the following P6 maths:

Anna, Belinda and Clare bought a vase and shared the cost equally among themselves. Clare did not bring her money, so Anna and Belinda paid for the vase first. Anna paid 0.25 more than what Belinda had paid. The following day, Clare paid her share to both Anna and Belinda.

a) Clare paid Belinda $6.55. How much did Clare pay Anna?

b) Clare’s brother bought a similar vase at the same shop during a sale and was given a disconunt of 20% of the price that Clare and her friends paid for. How much did Clare’s brother pay for the Vase?

Thank you
Firebird

[leesf]

Hi, appreciate if you could help this question from Kong Hwa practice papers.


A car and a truck were travelling from Town X to Town Y which were 375km apart. the car set off 2 hours later than the truck but arrived 1 hr 20min earlier. If the speed of the truck was 50km/h, find the time taken by the car to catch up with the truck.

Thanks

[Rockstar]

firebird:

Dear all


Good afternoon.

Please help me on the following P6 maths:

Anna, Belinda and Clare bought a vase and shared the cost equally among themselves. Clare did not bring her money, so Anna and Belinda paid for the vase first. Anna paid 0.25 more than what Belinda had paid. The following day, Clare paid her share to both Anna and Belinda.

a) Clare paid Belinda $6.55. How much did Clare pay Anna?

b) Clare's brother bought a similar vase at the same shop during a sale and was given a disconunt of 20% of the price that Clare and her friends paid for. How much did Clare's brother pay for the Vase?

Thank you
Firebird

This question can be solved easily with a model.

What they were supposed to pay.

A [ 1 unit ]

B [ 1 unit ]

C [ 1 unit ]


But they paid,

A [ 1 unit ][$6.55][0.25 units]

B [ 1 unit ][$6.55]

$6.55 +$6.55+0.25 units = 1 unit
0. 75 units=13.10

Clare paid $13.10 to Anna

b)

1 unit-------$13.10+$6.55= $19.65

3 units------$19.65 x 3 = $58.95

100% of the cost----$58.95

100%-20% of the cost -------58.95/100 x 80
80% of the cost------$47.16

Clare's brother paid $47.26 for the vase.


Are both my answers correct?

[Vanilla Cake]

leesf:

Hi, appreciate if you could help this question from Kong Hwa practice papers.

Is your child in Kong Hwa and is the best P6 class from BICEP?

leesf:

A car and a truck were travelling from Town X to Town Y which were 375km apart. the car set off 2 hours later than the truck but arrived 1 hr 20min earlier. If the speed of the truck was 50km/h, find the time taken by the car to catch up with the truck.

Car set off 2 hours later than truck but arrived 1 h 20 min earlier means difference = 3 h 20 min = 3⅓h
Time taken for truck to reach Town Y = 375÷50= 7½ h
Time taken for car to reach Town Y = 7½h - 3⅓h = 4⅙h (4 and 1/6 h)
Speed of the car = 375÷4⅙ = 90 km/h (375÷4 and 1/6 = 90 km/h)
Headstart by truck in 2 h = 50x2 = 100 km
Difference in speed = (90-50)km/h = 40 km/h
Time taken by the car to catch up with the truck = 100/40= 2½h

[Vanilla Cake]

firebird:

Dear all

Good afternoon.
Please help me on the following P6 maths:

Hi firebird,
Is this question from your DS's homework or from one of the top schools' 2010 P6 Prelim exam papers?

firebird:

Anna, Belinda and Clare bought a vase and shared the cost equally among themselves. Clare did not bring her money, so Anna and Belinda paid for the vase first. Anna paid 0.25 more than what Belinda had paid. The following day, Clare paid her share to both Anna and Belinda.
a) Clare paid Belinda $6.55. How much did Clare pay Anna?
b) Clare's brother bought a similar vase at the same shop during a sale and was given a disconunt of 20% of the price that Clare and her friends paid for. How much did Clare's brother pay for the Vase?

A : B : C
1 : 1 : 1
Multiply by 3
3 : 3 : 3

Total cost of the vase-> 9 units
Each person must pay 3 units

As C did not bring her money, A and B paid for the vase first in the ratio of :
A : B
1.25 : 1
Multiply by 4
5 : 4

Clare paid Belinda $ 6.55
4u-3u=u
u = $6.55

Clare paid Anna -> 5u-3u=2u
2u=2x$6.55 = $13.10
(a) Amount of money that Clare paid Anna = $13.10

Total cost of the vase = 9u = 9x$6.55=$58.95
Amount paid by Clare's brother after a discount of 20% -> 80/100x$58.95=$47.16
(b) Amount of money that Clare's brother paid for the vase = $47.16

I think this concept is called unchanged total, check it up in http://www.onsponge.com/forum/35-thinkingmathonsponge.html for similar questions or check with Chris Rogers.

Thks.