Q&A - P5 Math

[cimman]

tianzhu:

concerned1970:

2) Calvin had some marbles. He gave 63 of them to Danny and 2/5 of the remainder to Ellen. After that, he found that he still had 1/4 of his marbles left. A) What fraction of his marbles did he give to Danny? B) How many marbles did Calvin have at first?

Hi

You may work with units or MD.

¼ of marbles --------- 3 units

Total marbles -------- 12 units

7 units ------- 63
1 unit ------- 9

He gave to Danny 2/12 or 1/6 of his marbles.

Calvin had 108 (12*9) marbles at first.

Best wishes

I believe the question should be phrased: What fraction of his marbles did he give to Ellen ?

[tianzhu]

cimman:

I believe the question should be phrased: What fraction of his marbles did he give to Ellen ?

Hi

He gave to Danny 63/108 or 7/12 of his marbles.

I'll revise the earlier solution.

Thank you.

Best wishes

[concerned1970]

[quote=\"tianzhu\"][quote=\"concerned1970\"]

3) On a bus, there were 32 more females than males. At a particular bus stop, 12 females alighted from the bus and 4 males boarded the bus. There were twice as many females as males in the end.
a) What was the total number of males at the bus stop? b) How many females were there on the bus at first?


Q3)

A neat way to use is MD.

In the end

Male passengers ------ 1 unit + 4
Female passengers ------ 1 unit + 20(32-12)

2 units + 8 --------1 unit + 20
1 unit ------12

Total number of female passengers in the bus at first ------ 1 unit + 32 -------44

Hi. Sry i dun get this 2 parts. Pls elaborate. Sry to trouble u. Ty for yr efforts.

2 units + 8 --------1 unit + 20
1 unit ------12

[concerned1970]

There were 920 spectators in the sports hall watching a badminton match. After 2/5 of the children and 2/7 of the adults left the hall, the number of children and the number of adults remaining in the hall were the same. a) How many children remained in the sports hall? b) How many adults were there in the sports hall at first?

[tianzhu]

concerned1970:

3) On a bus, there were 32 more females than males. At a particular bus stop, 12 females alighted from the bus and 4 males boarded the bus. There were twice as many females as males in the end.
a) What was the total number of males at the bus stop? b) How many females were there on the bus at first?

Hi

I’ll add the MD later.

Please confirm your part (a).

For (a), we only know 4 male passengers boarded the bus at the particular bus stop.

If the question setter expected students to find out the number of male passengers in the bus after boarding, the answer is 16. (The bus will be at the bus stop before moving off to the next stop).

If he refers to only to the males at the bus stop before boarding , then the answer is 4.

Best wishes

[concerned1970]

tianzhu:

concerned1970:

3) On a bus, there were 32 more females than males. At a particular bus stop, 12 females alighted from the bus and 4 males boarded the bus. There were twice as many females as males in the end.
a) What was the total number of males at the bus stop? b) How many females were there on the bus at first?

Hi

I’ll add the MD later.

Please confirm your part (a).

For (a), we only know 4 male passengers boarded the bus at the particular bus stop.

If the question setter expected students to find out the number of male passengers in the bus after boarding, the answer is 16. (The bus will be at the bus stop before moving off to the next stop).

If he refers to only to the males at the bus stop before boarding , then the answer is 4.

Best wishes

Hi. You're right in saying 16 male passengers in the bus after boarding. Tysm.

[tianzhu]

Hi


Hope this helps.

Best wishes

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[tianzhu]

concerned1970:

There were 920 spectators in the sports hall watching a badminton match. After 2/5 of the children and 2/7 of the adults left the hall, the number of children and the number of adults remaining in the hall were the same. a) How many children remained in the sports hall? b) How many adults were there in the sports hall at first?

Hi

You may use “Equal Concept”.

3/5 of the children ------ remained in the hall
5/7 of the adults ------ remained in the hall

A common multiple of 3 and 5 ------- 15

Total number of children ------- 25 units
Total number of adults ------- 21 units

46 units ------- 920
1 unit ------- 20

Number of children remaining in the hall ------- 15 units ------- 300

Number of adults in the sports hall at first ------- 21 units ------- 420

Best wishes

[concerned1970]

So sry i dun get u. Why did we have to get common multiple for 3 and 5?

[tianzhu]

concerned1970:

So sry i dun get u. Why did we have to get common multiple for 3 and 5?

Hi

I believe your child should have learned the “Equal concepts” from his school teacher.

In this question, one part of children is not the same as one part of children as each box in the MD is of different sizes as they represent different objects.

We want to make a comparison so we equalise the numerators of the two fractions 3/5 and 5/7.

3 and 5 have a common multiple of 15.

Please get your child to draw a model as it might help him/her to see better.

I am sorry, I don't have time to draw one now.

Best wishes