Tutor MathsGuru: Ask me for your burning Maths questions!

[Dharma]

Almighty:

Thank u very much for the reply but,Very sorry Dharma.I Still cannot understand the things written in red. Can u plssss clarify?

Dharma:

[quote=\"Almighty\"]One problem.... Please help!!

Two identical containers X and Y have sugar and rice in the ratio 1 : 3 and 2:5 respectively. Tank Z contains some rice only. All the sugar in both containers are put into tank Z. The ratio of the sugar to the rice in tank Z is 3:5. How much sugar is in container X at first if there are 500 g of rice in Tank Z?

Tank X
s:r
1:3 why DID U MULTIPLY BY 7 ?

Tank Y
S :R
2:5 why DID U MULTIPLY BY 4

Tank X
S : R = 7 : 21

Tank Y
S : R = 8 : 20
Amt of S in
Tank Z = 7u + 8u = 15u

Tank Z
S : R = 3 : 5 = 15 : 25

25p = 500g
15p = 15u = 300g
1u = 20g
7u = 140g (Amt of sugar in Tank X)

# Use assumed that 5 parts(rice) in Tank Z = 500g. That is where u went wrong

[/quote]Tank X and Y are IDENTICAL containers. So, total qty of sugar and rice must be the same in both containers. (i.e. 28u).

[YLH88]

Hi all,


Need help with the below speed questions

1) PeiHwa P6 SA1 2009 Paper 2 Qn 4
Auntie Melanie is walking on the platform of an MRT station at 120 m/min.
A train overtakes her completely in 25 seconds.
The length of the train is 300 metres.
How fast is the train ?
(Ans : 14 m/s)

2) PeiHwa P6 SA1 2009 Paper 2 Qn 13
A lorry left Happy Town for Bayview Town at 60 km/h.
Two hours later, a sports car travelling at 140 km/h left Happy Town for Bayview Town too.
The sports car caught up with the lorry at a distance of 20 km away from Bayview Town.
Find the distance between the two towns.
(Ans : 230 km)

Thank you very much!

[Vanilla Cake]

YLH88:

1) PeiHwa P6 SA1 2009 Paper 2 Qn 4

Auntie Melanie is walking on the platform of an MRT station at 120 m/min.
A train overtakes her completely in 25 seconds.
The length of the train is 300 metres.
How fast is the train ?

[MRT Train]---50m--->-----300m---->
[A.Melanie]---50m--->

120m/min = 2 m/sec (Divide 120m by 60)
In 25 seconds, Auntie Melanie walked = 2 m/sec x25 seconds = 50 m
In 25 seconds, MRT train travelled = 50m+300m =350 m where 300 m is the length of train
Average speed of train = 350m divided by 25 seconds = 14 m/s

YLH88:

2) PeiHwa P6 SA1 2009 Paper 2 Qn 13
A lorry left Happy Town for Bayview Town at 60 km/h.
Two hours later, a sports car travelling at 140 km/h left Happy Town for Bayview Town too.
The sports car caught up with the lorry at a distance of 20 km away from Bayview Town.
Find the distance between the two towns.

Use common distance and the relationship between speed and time (inverse ratio) concept

Ratio of speed
Lorry : Car
60 : 140
3 : 7

Ratio of time
Lorry : Car
7 : 3

Difference in time = (7-3)units = 4 units
4 units = 2 hours
1 unit = 0.5 hour
7 units = 3.5 hours (Time travelled by lorry)

Distance travelled by lorry = 60 km/hx3.5 hours = 210 km
Distance between the two towns = (210+20) km = 230 km

OR

Headstart by lorry = 60 km/h x2 hours = 120 km
Difference in speed = (140-60) km/h = 80 km/h
120 km divided by 80 km/h = 1.5 hours
Distance travelled by car in 1.5 hours to catch up with lorry = 1.5x140=210km
Distance between the two towns= (210+20)km = 230 km

[YLH88]

Hi VC,


Thank you very much for the solution!!

Your school term starting next week too ? Enjoy your last week of holiday :lol:

[Almighty]

Hi dharma,

Thank u for yr explanation for the "Identical Tank" problem n other speed problem.
Regarding the typo error, i edited there again. Pls help on tht too.

[Almighty]

Dharma:

Herbie:

Hi Maths Monster

Sorry, I dun understand how you workout part b.

b) From power of 4 to 7, the pattern is 0625, 3125, 5625, 8125 and it repeats itself for every 4 power. Therefore, 210/4 = 52 reminder 2, so the last 4 digits is 5625 and its sum = 5 + 6 + 2 + 5 = 18

can explain in more detail?

HI,
I cannot trace the problem for this solution.Can anyone give me the link for this problem?

[Tang]

Dharma:

Almighty:

Thank u very much for the reply but,Very sorry Dharma.I Still cannot understand the things written in red. Can u plssss clarify?

[quote=\"Dharma\"]Tank X
S : R = 7 : 21

Tank Y
S : R = 8 : 20
Amt of S in
Tank Z = 7u + 8u = 15u

Tank Z
S : R = 3 : 5 = 15 : 25

25p = 500g
15p = 15u = 300g
1u = 20g
7u = 140g (Amt of sugar in Tank X)

# Use assumed that 5 parts(rice) in Tank Z = 500g. That is where u went wrong

Tank X and Y are IDENTICAL containers. So, total qty of sugar and rice must be the same in both containers. (i.e. 28u).[/quote]
Hello,

I think the question should use 'are completed filled with' instead of 'have'

Two identical containers X and Y have sugar and rice in the ratio 1 : 3 and 2:5 respectively.

[tianzhu]

Almighty:

2) David and Michael drove from Town A to Town B at different speeds. Both didnot change their speeds throughout their journeys.
David started his journey 30 minutes earlier than David. When Michael reached Town B 50 minutes earlier than David, David had travelled 4/5 of the journey and was 75 Km away from Town B.a) What was the distance between Town A and Town B?
b) How many Kilometres did David travel in 1 hour?
c) What was the time taken by Michael to travel from Town A to Town B?

Hi

You may want to take a look at the underlined sentence. Is there a typo error?

Best wishes

[dolphinsiah]

Good Afternoon MathsGuru,


Please help to solve below P5 Maths:

There were 4 times as many chairs as tables in a store room. After 67 chairs and 8 tables were taken away, there were twice as many tables and chairs left in the store room.
How may tables were there in the store room at first.

Thanks in advance :lol:

[kwcllf]

ruyu:

Vanilla Cake:

[quote=\"ruyu\"]dont understand :? care to explain?

Thks for pointing out, I have amended the workings.
Average speed should be 3 km/h

LCM of 2 and 6 is 12

Time taken to climb uphill @ 2 km/h = 12/2 = 6h
Time taken to go downhill @ 6 km/h = 12/6 = 2h
Total time taken = 8h
Total distance covered = 12x2 = 24 km
Average speed for the entire trip = 24km/8h = 3 km/h

no seriously i dont understand[/quote]How about the following explanation:

Downhill = 6km/h
In other words, 1h = travels 6km


Uphill (2km/h): To travel 6km, time taken = 3h
Downhill: To travel 6km, time taken = 1h
Total Distance travelled = 6km+6km = 12km
Total Time taken = 3h+1h = 4h

Therefore, Average speed = 12km/4h = 3km/h