Tutor MathsGuru: Ask me for your burning Maths questions!

[livewith_vanilla]

kwcllf:

Hi,


Please help with the following question:

Andy, Benny and Calvin have 150 buttons altogether.
If Andy gives 3/7 of his buttons to Benny and Benny gives 32 buttons to Calvin and Calvin gives 26 buttons to Andy, they have the same number of buttons.

How many buttons do they have at first?

(I got the answers as Andy=42, Benny=64 and Calvin=44 by using algebra. But I am afraid my P4 son may not understand. Hope someone can help with an alternative solution).
Thanks!

Since the three boys give each other and not give away, the TOTAL number of marbles stay the same(eg. 150)

Hence, 150/3=50

Thus each boy has the same number of marbles left.

Andy:

Calvin gives Andy 26 marbles.

Thus, 50-26=24

In the first place, Andy gave Benny 3/7 of his marbles, before Calvin gave him any marbles.

Thus, Andy has (1-3/7=4/7) marbles left.

4u->24
1u->24/4=6
7u->6x7=42

Benny:
Andy gave 3u of his marbles to Benny.

Thus,

1u(of Andy)->6
3u(of Andy)->6x3=18

Andy gave Benny 18 marbles.

50+32=82

This is the number of marbles Benny would have if he did not give Calvin any marbles.

However, since Andy gave Benny some marbles, we have to substract 18 marbles from 82 marbles.

82-18=64

Benny has 64 marbles.

Calvin:

The Long Way:

Since Calvin gave Andy 26 marbles,

50+26=76

Calvin would have 76 marbles if he did not give any marbles to Andy.

However, Benny gave Calvin 32 marbles.

Thus,

76-32=44

Calvin would have 44 marbles.


Short way:

Since we found out Andy has 42 marbles and Benny has 64 marbles, we just need to take the total marbles subtract the sum of Andy's and Benny's marbles.

42+64=106
150-106=44

Calvin would have 44 marbles.

[beauty queen]

Dear MathsGuru please help me with these questions,


1) Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles.How many red and blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in container B are red.

2)There are some black and white marbles in a bag. If 20 black marbles are removed from the bag, the total number of marbles left will be 7 times the number of black marbles left. If 50 white marbles are removed from the bag, the total number of marbles left will be 5 times the number of black marbles left. How many marbles are there in the bag.

Please help

[super star]

please help me with this problem

Tank p with 40cm by 30cm base is filled with water till it reaches the height 55cm .water was then poured from tank p to tank q with base 100cmby20cm, untill the height of the water level in tank p became twice that of the water level in tank q.find the volume of water in tank q. give your ans in liters.

[livewith_vanilla]

beauty queen:

Dear MathsGuru please help me with these questions,


1) Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles.How many red and blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in container B are red.

2)There are some black and white marbles in a bag. If 20 black marbles are removed from the bag, the total number of marbles left will be 7 times the number of black marbles left. If 50 white marbles are removed from the bag, the total number of marbles left will be 5 times the number of black marbles left. How many marbles are there in the bag.


Hi your questions from ACS Maths Prelim paper right?

Please refer to here:

http://www.kiasuparents.com/kiasu/content/some-math-questions-and-answers
Please help

[starlight1968sg]

super star:

please help me with this problem

Tank p with 40cm by 30cm base is filled with water till it reaches the height 55cm (as per the picture given the tank is taller than 55cm) .water was then poured from tank p to tank q with base 100cmby20cm, untill the height of the water level in tank p became twice that of the water level in tank q.find the volume of water in tank q. give your ans in liters.

What is the ans?

I dont really understand the sentence:
\"untill the height of the water level in tank p became twice that of the water level in tank q\"

Volume of water in tank p = 40*30*55= 66 litres.
Volume of water in tank q = 100*20*(55/2) = 55 litres.

[livewith_vanilla]

super star:

please help me with this problem

Tank p with 40cm by 30cm base is filled with water till it reaches the height 55cm .water was then poured from tank p to tank q with base 100cmby20cm, untill the height of the water level in tank p became twice that of the water level in tank q.find the volume of water in tank q. give your ans in liters.

55x40x30=66000

40x30=1200
100x20=12000
12000+1200=13200
66000/13200=5
5x2=10
10x100x20=20000

20000cm3 = 20L

Ans:20L

others please double confirm answer.

[livewith_vanilla]

starlight1968sg:

super star:

please help me with this problem

Tank p with 40cm by 30cm base is filled with water till it reaches the height 55cm (as per the picture given the tank is taller than 55cm) .water was then poured from tank p to tank q with base 100cmby20cm, untill the height of the water level in tank p became twice that of the water level in tank q.find the volume of water in tank q. give your ans in liters.

What is the ans?

I dont really understand the sentence:
\"untill the height of the water level in tank p became twice that of the water level in tank q\"

Volume of water in tank p = 40*30*55= 66 litres.
Volume of water in tank q = 100*20*(55/2) = 55 litres.

My interpretation of the questions is as of below:

Tank P was holding 66 litres of water at first.
Then some water was \"poured\" over to tank Q.
This person pours the water until the height of water in tank Q was twice of the height of the remaining water in tank P.

Something like this.

[maths6a]

livewith_vanilla:

super star:

please help me with this problem

Tank p with 40cm by 30cm base is filled with water till it reaches the height 55cm .water was then poured from tank p to tank q with base 100cmby20cm, untill the height of the water level in tank p became twice that of the water level in tank q.find the volume of water in tank q. give your ans in liters.

55x40x30=66000

40x30=1200
100x20=12000
12000+1200=13200
66000/13200=5
5x2=10
10x100x20=20000

20000cm3 = 20L

Ans:20L

others please double confirm answer.

You made a calculation error with \"100x20=12000\"
it should be 2000

so answer should be 30 litres

Amount of water you have in tank p which you want to pour into p and q in such a way that the height in p is twice q so let the height in q be 1 unit and the height in p be two units.

55x40x30=66000 (amt of water in p)

vol to be filled in p + vol to be filled in q = 66000 ml

40x30x2units +100x20x 1 unit = 66000 ml
2400 units + 2000 units = 66000 ml
4400 units = 66000 ml
1 unit = 15 cm
2000 x 15 = 30000ml = 30 litres

[Kiasu Friend]

Please provide a solution for the following problem: (MGS Prelim question)


The following pattern is created with 4 letters, A,B,C and D.
A B C D A A B B C C D D A A A B B B C C C D D D………. ?
Following the above pattern, what is the 230th letter? (A, B, C or D)?

This has appeared in the MCQ section carrying only 2 marks. Hence I believe there should be a fast and easy way to work this out.

Can anyone help out please?

Thank you all.

[elkniwt]

Kiasu Friend:

Please provide a solution for the following problem: (MGS Prelim question)


The following pattern is created with 4 letters, A,B,C and D.
A B C D A A B B C C D D A A A B B B C C C D D D………. ?
Following the above pattern, what is the 230th letter? (A, B, C or D)?

This has appeared in the MCQ section carrying only 2 marks. Hence I believe there should be a fast and easy way to work this out.

Can anyone help out please?

Thank you all.

Hi,

This method is not very short. Just sharing so that others can brainstorm and improve on it ...

We can divide the series of ABCD into sets :
Set 1 - A B C D ( i.e. 4 letters , each letter repeated 1 time)
Set 2 - A A B B C C D D ( 8 letters , each repeated 2 times)
Note that the number of letters is in a simple sequence,
4, 8, 12, 16, ...
The 10th term (which is the number of letters in Set 10) = 40
Sum of 4 + 8 + ... + 40 = (4 + 40) x (10/2) = 220
Hence the 230th letter is in Set 11 where each letter is repeated 11 times, hence it is A.

Regards.