Tutor MathsGuru: Ask me for your burning Maths questions!

[Dharma]

YLH88:

Hi VC, Dharma,


Thank you so much for the solution !! Am trying to 'disgest' and understand the method

May need to trouble you again if still blur .. :?

Hope this will help

http://www.postimage.org/image.php?v=Ts2JJbS

[nettie]

I had another question.


A 60 km long train enter into an underground tunnel. it is traveling at a speed of 72km/h. It takes 2 mins to emerge entirely from the tunnel. How long is the undergound tunnel?

[Dharma]

nettie:

I had another question.


A 60 km long train enter into an underground tunnel. it is traveling at a speed of 72km/h. It takes 2 mins to emerge entirely from the tunnel. How long is the undergound tunnel?

Is the length of the train 60km or 60m?

[nettie]

Dharma:

nettie:

I had another question.


A 60 km long train enter into an underground tunnel. it is traveling at a speed of 72km/h. It takes 2 mins to emerge entirely from the tunnel. How long is the undergound tunnel?

Is the length of the train 60km or 60m?

I was told verally that it is 60km! i was wondering how can the train be so long! hahaha

[Dharma]

nettie:

Dharma:

[quote=\"nettie\"]I had another question.


A 60 km long train enter into an underground tunnel. it is traveling at a speed of 72km/h. It takes 2 mins to emerge entirely from the tunnel. How long is the undergound tunnel?

Is the length of the train 60km or 60m?

I was told verally that it is 60km! i was wondering how can the train be so long! hahaha[/quote]When the train emerges entirely from the tunnel of length L(tunnel) in 2 minutes, the distance travelled by the train will be the sum of the length of tunnel L(tunnel) and length of the train, L(train)

L(tunnel) + L(train) = Speed of train (72km/h) x Time taken (2 mins/60 = 1/30hrs)

L (tunnel ) = 72/30 km – 60 km = 2.4km – 60km [ IMPOSSIBLE!!!!]

The length of train is likely to be 60m
L(tunnel) = 2.4km – 0.06km = 2.34km

[Herbie]

Hi I have a speed qn. Can help?


Town B is located between Town A and C.
At 2pm, a train left Town B and travelled towards Town C.
2.5 hr later, another train left Town B for Town A.
At 6pm, the two trains were 569km apart.
What was the speed of the train travelling towards Town C if it was going at 35km/h faster than the other train?

Tx

[Vanilla Cake]

Dharma:

nettie:

[quote=\"Dharma\"]
Is the length of the train 60km or 60m?

I was told verally that it is 60km! i was wondering how can the train be so long! hahaha

When the train emerges entirely from the tunnel of length L(tunnel) in 2 minutes, the distance travelled by the train will be the sum of the length of tunnel L(tunnel) and length of the train, L(train)

L(tunnel) + L(train) = Speed of train (72km/h) x Time taken (2 mins/60 = 1/30hrs)

L (tunnel ) = 72/30 km – 60 km = 2.4km – 60km [ IMPOSSIBLE!!!!]

The length of train is likely to be 60m
L(tunnel) = 2.4km – 0.06km = 2.34km[/quote]Hi nettie,
Your question is similar to http://www.wendykoh.com/08/primary6-scgssa2-maths.pdf and that question was posted by http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=280&postdays=0&postorder=asc&start=840 on Thu Sep 24, 2009 3:46 pm and the correct method used to solve this problem sum was confirmed by our revered http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=280&postdays=0&postorder=asc&start=840 on Thu Sep 24, 2009 6:58 pm.
Pls recheck the source while waiting for Mathsguru' solution.

Submitted by VC's mum

[Vanilla Cake]

Herbie:

Hi I have a speed qn. Can help?


Town B is located between Town A and C.
At 2pm, a train left Town B and travelled towards Town C.
2.5 hr later, another train left Town B for Town A.
At 6pm, the two trains were 569km apart.
What was the speed of the train travelling towards Town C if it was going at 35km/h faster than the other train?

Tx

113 km/h

[Herbie]

huh! Can show the steps?

[Vanilla Cake]

Herbie:

huh! Can show the steps?

Sure.

(ux1.5)+(u+35)4= 569
Solve for u and you will get u =78 km/h
(78+35) km/h = 113 km/h

Pls kindly wait for Dharma/Mathsguru's detailed solution.
Thanks.

Submitted by VC's mum.