Q&A - PSLE Math

[tianzhu]

cycjca:

1) Mrs Chua has just enough money to buy 4 kg of crabs & 3 kg of prawns. However she bought 2 kg of crabs & 4 kg of prawns & had $4.50 left. If she exchanged the 3 kg of crabs with 3 kg of prawns, how much money would she have left?

If 2kg of crabs is changed to 3kg of crabs, here's the solution.

Hope this helps.

Best wishes

http://farm5.static.flickr.com/4133/5019157330_02c85ba4c0_b.jpg\">

[tianzhu]

Hi


Hope this helps.

Best wishes.

http://farm5.static.flickr.com/4147/5019157380_593d6e70b1_b.jpg\">

[Yu Xuan]

cycjca:

1) Mrs Chua has just enough money to buy 4 kg of crabs & 3 kg of prawns. However she bought 2 kg of crabs & 4 kg of prawns & had $4.50 left. If she exchanged the 3 kg of crabs with 3 kg of prawns, how much money would she have left?

Using the numbers as Tianzhu
This is how I did it;

4C + 3P = 0 (amt of money left)
3C + 4P = 4.50 (amt of money left)

Comparing the two types of spending above;
For every 1C he exchange for 1P, he will also get $4.50 left, i.e
1C = 1P + 4.50
3C = 3P + 13.50

Hence,
3P + 4P = $4.50 + $13.50 = $18

[Yu Xuan]

cycjca:

2)Mr Tan had 200 apples and oranges.
1/3 of the apples and 1/4 of the oranges were rotten. He threw away 60 rotten fruits altogether. How many rotten oranges were there?

R denotes orange

1 A + 1 R= 200
1/3 A +1/4 R = 60

multiply the second equation by 3 so that we can have 1 whole of A.
1A + 3/4R = 180

Comparing this equation with the first equation;
1/4 R --> 200 - 180 = 20

[Rockstar]

Mr Tan had 200 apples and oranges.

1/3 of the apples and 1/4 of the oranges were rotten. He threw away 60 rotten fruits altogether. How many rotten oranges were there?



http://postimage.org/image/22o2e538/

[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)

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.

[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.