Q&A - PSLE Math

[kiasiparent]

Vanilla Cake:

suiyuan:

A bus and a car travelled from Town X to Town Y. The bus left Town X at 10.48pm and it took 5 hours to reach Town Y. The car started 30 minutes later than the bus and it took 4 hours to reach Town Y. At what time did the bus catch up with the bus?

Hi suiyuan,

I think that there is a typographical error in your question. I interpret as \"At what time did the car catch up with the bus?\" Based on this assumption, here is the solution :

Bus
5 h -> Whole journey
1 h -> 1/5 journey
1/2 h -> 1/10 journey

Car
4 h -> Whole journey
1 h-> 1/4 journey

Difference in distance travelled in 1 h ->
1/4 - 1/5
=5/20 - 4/20
=1/20 of the journey

Time needed to catch up-> 1/10 divide by 1/20
1/10 x 20/1
= 2 h

Draw a timeline :
11.18 pm...............2 h ...............1.18 am

The car caught up with the bus at 1.18 am

Pls confirm if my answer is correct ?
Thks.

correct.

[suiyuan]

Hi Vanilla cake


I’ll revised the question to correct error.Your answer is correct.
Thank you

[mathsparks]

I’ve a question on calculation of carpark charges. A man drives his car into carpark A at 4:30pm and leaves at 6:30pm. How much does he have to pay if the carpark charges $1 an hour or part thereof and $3 per entry after 5pm.


The answer could either be:
1) $1 (first half hr) + $3 (per entry) = $4

or
2) $1x2 (2 hrs) = $2

Since different carparks in SG calculate differently, both answers should be accepted.

Any comments?

[ChiefKiasu]

mathsparks:

I've a question on calculation of carpark charges. A man drives his car into carpark A at 4:30pm and leaves at 6:30pm. How much does he have to pay if the carpark charges $1 an hour or part thereof and $3 per entry after 5pm.


The answer could either be:
1) $1 (first half hr) + $3 (per entry) = $4

or
2) $1x2 (2 hrs) = $2

Since different carparks in SG calculate differently, both answers should be accepted.

Any comments?

This is a business modeling question, not a PSLE math problem :lol:

The first answer is correct. It's 4 bucks, baby, and I think it's pretty much the same answer all over Singapore .

[mathsparks]

Exactly chief. It should not be a psle qn. One of the 2007 top school papers has a similar qn. To quote my experience in United Sq carpark.


I park there from 4:50 till around 7:20pm. I couldn’t figure out how the charges came up to 5+.

So now I park from 4:50 till 6:50pm and wait for my kid outside the building and the charges comes up to 3+. Econ. crisis. Penny pinching.

So I think united sq charges is a combination of ans 1 and 2.

[mathsparks]

1 more qn. and possibly many more from me in the run up to psle. thanks for helping!


From Henry Park P6 SA1 2007

Ans is 360.

http://farm4.static.flickr.com/3617/3525348926_e2cf9bb25f_b.jpg\">

[small]

Hope this help, please correct me if I was wrong.

a) 11:30am to 3:30pm = 4 hours

Van was 80 km/hour
4 x 80 = 320 km

Van was 320 km from t=Town X

b) truck started 2 hours later which was 1:30pm

1:30pm to 3:30pm = 2 hours

Truck was 54 km/hour
2 x 54 = 108 km

At 3:30 pm:
Van was (350-320)km = 30km away to Town Y
Truck was 108 km away from Town Y

108 – 30 = 78 km

So the distance between the van and the truck at 3:30 pm was 108 km

[Vanilla Cake]

small:

Hope this help, please correct me if I was wrong.

a) 11:30am to 3:30pm = 4 hours

Van was 80 km/hour
4 x 80 = 320 km

Van was 320 km from t=Town X

b) truck started 2 hours later which was 1:30pm

1:30pm to 3:30pm = 2 hours

Truck was 54 km/hour
2 x 54 = 108 km

At 3:30 pm:
Van was (350-320)km = 30km away to Town Y
Truck was 108 km away from Town Y

108 – 30 = 78 km

So the distance between the van and the truck at 3:30 pm was 108 km

(a) 320 km

(b)Distance that the truck had travelled-> 54 X 2 = 108 km
Distance between the truck and van-> (108+320)-350
= 428-350
= 78 km

[mathsparks]

Thanks vanilla cake and small for your help. Realise i typed the wrong answer. For (a) it should be 320km and (b) 78km.


Thanks. I've one more question. Ans is 360.
http://farm4.static.flickr.com/3654/3525605596_a43c5698aa_o.png\">

[Vanilla Cake]

mathsparks:

Thanks vanilla cake and small for your help. Realise i typed the wrong answer. For (a) it should be 320km and (b) 78km.


Thanks. I've one more question. Ans is 360.
http://farm4.static.flickr.com/3654/3525605596_a43c5698aa_o.png\">

Hi Mathsparks,
Yr qn and solution can be found in this http://prischoolmaths.blogspot.com/search/label/Maths-Percentage
Reference : Maths - Percentage dated 8 Feb 2009.

Hope this helps.