ANOTHER PRI SCH MATHS QN

[Shorty]

David has 5 times as many marbles as Tim. If he gives 78 marbles to Tim, he will still have twice as many marbles as Tim.

 

1) how many marbles do they have altogether?

2) how many more marbles does DAvid have than Tim now?

[Acieed]

1) 156

2) 26

[Coltplussport]

1)468

2)156

[Akari_ph]

David has 5 times as many marbles as Tim. If he gives 78 marbles to Tim, he will still have twice as many marbles as Tim.

 

1) how many marbles do they have altogether?

2) how many more marbles does DAvid have than Tim now?

 

1) 468

2) 156

[Shorty]

wat r the steps pls...

[Quirky]

total 6 units of marbles.

initially: split 5-1.

final; split 4-2.

so 1 unit is 78 marbles.

 

1) 6 units is 78 x 6 = 468

2) 2 units = 78 x 2 = 156

 

 

David has 5 times as many marbles as Tim. If he gives 78 marbles to Tim, he will still have twice as many marbles as Tim.

 

1) how many marbles do they have altogether?

2) how many more marbles does DAvid have than Tim now?

Edited October 18, 2011 by Quirky

[Shull]

David has 5 times as many marbles as Tim. If he gives 78 marbles to Tim, he will still have twice as many marbles as Tim.

 

1) how many marbles do they have altogether?

2) how many more marbles does DAvid have than Tim now?

 

Before:

David = 5 units

Tim = 1 unit

 

Now:

Davic give 1u to Tim

David = 4u

Tim = 2u

 

therefore, 1u = 78 marbles..

 

solved..

[Akari_ph]

wat r the steps pls...

 

No. of marble Tim has = X

No. of marble David has = 5X

 

5X-78 = 2(X+78)

Ans: X = 78

 

Together = 6X = 468

Diff = 5X-3X = 156

[Shorty]

wow...that is easier than i tot.. hehe. long time nvr do any maths prob. thks guys

[Joseph22]

wow...that is easier than i tot.. hehe. long time nvr do any maths prob. thks guys

yeah. primary school math is look difficult but actually very easy solution one.

 

we find it difficult because we learn too many formulae liao. and forgot the basic.

 

ever got penalise before by teacher for using a simple formulae to solve a difficult sum... because the quiz on top got put what quiz it is

Edited October 18, 2011 by Joseph22

[Shorty]

yeah la...whenever i see this kind of qn...tot must use some chim formula or something...

 

but if jus tink simple, can solve easily. haiz... brain rusty liao

[SimonTan]

What is the logic one unit is lequal for David n Tim?

 

[Shorty]

when using units, i believe the no should b the same...if not...how to use units?

[Joseph22]

when using units, i believe the no should b the same...if not...how to use units?

when number is different. you have to increase the number of units lor.

 

question like A is 5 times of B and B is 2 times of C.

 

you will have to base everything off C.

 

more complicated one require more thinking though.

[SimonTan]

The assumption of the unit remaining the same value after giving away 78 or adding 78 is not logical. Or am I missing something?

 

[Shorty]

the simple explanation is... total david has 5 times of tim. means total got 6 units. n after giving 78, david has double. so 5-1=4. n 1+1= 2. so, it is double.

 

don need to tink too much.

[Quirky]

The number of units also need to be common multiple of 6 (from the 5 times), and 3 (from the twice as many).

In this case, it's 6. It's ok if you use 12, 18, ... and so on.

 

 

the simple explanation is... total david has 5 times of tim. means total got 6 units. n after giving 78, david has double. so 5-1=4. n 1+1= 2. so, it is double.

 

don need to tink too much.

 

[Kelvingoh45]

Need to draw model.