Q&A - P4 Math

[chloecube]

Nebbermind:

chloecube:

jon and Dan have the same amount of money. After jon received twice the amount of money he had and Dan spent $8, joh now has 4 times the money Dan has. How much did Dan have at the beginning?

Originally,

Dan = (U +
Jon = (U +

After,

Dan = U
Jon = (U + + (U + + (U +

Therefore,

4U = 3U + 24
U = 24

They had (U + = 32 in the beginning

got it! thks

[Thein]

http://i48.tinypic.com/m8ipm1.jpg\">

[chloecube]

James has some marbles. If he packed them into box of 6, he will have 2 left. If he pack them in box of 7, he will be short of 11. How many marbles does he have?


Method 1:
If I do in multiples of 6&7, my answer is 38
Method 2:
If I draw model, answer is 80.

So which is the correct answer?

[tianzhu]

chloecube:

James has some marbles. If he packed them into box of 6, he will have 2 left. If he pack them in box of 7, he will be short of 11. How many marbles does he have?


Method 1:
If I do in multiples of 6&7, my answer is 38
Method 2:
If I draw model, answer is 80.

So which is the correct answer?

Hi

The answer is 80 and the number of boxes is 13.

Please go through your MM again, it should give you the same answer.

(Multiples of 6) + 2

(Multiples of 7) - 11

Best wishes

[php]

chloecube:

James has some marbles. If he packed them into box of 6, he will have 2 left. If he pack them in box of 7, he will be short of 11. How many marbles does he have?


Method 1:
If I do in multiples of 6&7, my answer is 38
Method 2:
If I draw model, answer is 80.

So which is the correct answer?

Box of 6 --> +2
Box of 7 --> -11

No of boxes --> (11 + 2) div (7 - 6) = 13

No of marbles --> (6 x 13) + 2 = 80

Check --> (7 x 13) - 11 = 80

Ans : 80

[Thein]

http://i49.tinypic.com/mlawz.jpg\">

[chloecube]

tianzhu:

chloecube:

James has some marbles. If he packed them into box of 6, he will have 2 left. If he pack them in box of 7, he will be short of 11. How many marbles does he have?


Method 1:
If I do in multiples of 6&7, my answer is 38
Method 2:
If I draw model, answer is 80.

So which is the correct answer?

Hi

The answer is 80 and the number of boxes is 13.

Please go through your MM again, it should give you the same answer.

(Multiples of 6) + 2

(Multiples of 7) - 11

Best wishes

Hi tianzhu,

if i use mof 6 and mof 7,
mof 6 - ...36,42,48,54,60,66,72,78
(+2) -...38,44,50,56,62,68,74,80

mof 7 - ...35,42,49,56,63,70,77,84,91
(-11) -...24,31,38,45,52,59,66,73,80

u notice the 38 and 80 appear in both mof 6 and 7
so i am kind of confused why the answer is 80 and not 38

another thing is, for this kind of question, is using mof 6 and 7 better or thru drawing of model?

[Nebbermind]

If there were 38, there would have been 6 boxes giving a total of 36 and 2 left.


If you put 7 into the boxes, you can fill 5 of the 6 boxes and will be 4 short for the sixth box, not 11.

[chloecube]

Thein:

http://i49.tinypic.com/mlawz.jpg\">

thks thein,

so the number of boxes have to be the same?

sorry for being slow, i am trying to understand what the question is asking. they ask for the number of marble and not boxes, so i thought the differences in boxes does not matter.

if i take 38 marbles ; mof 6 wil have 6 boxes and mof of 7 will have 7 boxes..
but if i take 80 marbles, number of boxes will be the same

i am confusing myself..

[CoffeeCat]

chloecube:

Thein:

http://i49.tinypic.com/mlawz.jpg\">

thks thein,

so the number of boxes have to be the same?

sorry for being slow, i am trying to understand what the question is asking. they ask for the number of marble and not boxes, so i thought the differences in boxes does not matter.

if i take 38 marbles ; mof 6 wil have 6 boxes and mof of 7 will have 7 boxes..
but if i take 80 marbles, number of boxes will be the same

i am confusing myself..

The question might not be too clear. However \"11 left when packed in boxes of 7\" suggests that the number of boxes is fixed beforehand. Otherwise it should be \"4 left when packed in boxes of 7\".
This is an example of an excess-shortage problem as exemplified by terry chew's books, where the number of groups is fixed.
If the number of groups is not fixed, then the question will have infinite number of answers and additional restriction should be stated.
(Answers can be 38, 80, 122, ... just add 42 to get the next possible answer)