Q&A - P4 Math

[MathIzzzFun]

thmejlfm:

Please help.


In a group of children, the mean age of the children is 10 years. If the mean age of the 8 boys was 15 years, the mean age of the girls was6 years. How many children were there altogether?

Hi

Total excess above average = Total shortfall below average.

8 x (15-10) = N x (10-6)
N= 10 --> 10 girls, total 10 + 8 = 18 children.

cheers.

[MathIzzzFun]

thmejlfm:

2nd question.


44 boys and 47 girls want to school camp. The pupils were put into groups. There was an equal no. Of pupils in each group.
A) how many groups were there?

In each group, the no of boys was 1 more or1 less than the no of girls,
B) how many groups had more girls than boys?

Hi

some information is missing.. for eg. For A) it can be either 7 groups of 13 children or 13 groups of 7 children

B) For 13 groups with 7 children each, each group will have either 4 boys/3 girls or 3 boys/4 girls

44 boys --> 44/13 = 3R5. So, there are 5 groups with 4 boys/3 girls and 8 groups with 3 boys/4 girls ie 8 groups with more girls.

For 7 groups with 13 children each, each group will have either 7 boys/6 girls or 6 boys/7 girls.

44 boys --> 44/7 = 6R2. So, there are 2 groups with 7 boys/6 girls and 5 groups with 6 boys/7 girls ie 5 groups with more girls.

cheers.

[thmejlfm]

Hi, thanks for the reply.


One of friends told my dd, was

8 x 15 = 120 (boys total)
G x 6 = 6G (girls total)

120 + 6G/8+G = 10
120 + 6G = 80 + 8G
40 =2G
G = 20

So, total children = 28.

So, which one is correct?

MathIzzzFun:

thmejlfm:

Please help.

In a group of children, the mean age of the children is 10 years. If the mean age of the 8 boys was 15 years, the mean age of the girls was6 years. How many children were there altogether?

Hi

Total excess above average = Total shortfall below average.

8 x (15-10) = N x (10-6)
N= 10 --> 10 girls, total 10 + 8 = 18 children.

cheers.

[atutor2001]

thmejlfm:

Hi, thanks for the reply.


One of friends told my dd, was

8 x 15 = 120 (boys total)
G x 6 = 6G (girls total)

120 + 6G/8+G = 10
120 + 6G = 80 + 8G
40 =2G
G = 20

So, total children = 28.

So, which one is correct?

MathIzzzFun:

[quote=\"thmejlfm\"]Please help.

In a group of children, the mean age of the children is 10 years. If the mean age of the 8 boys was 15 years, the mean age of the girls was6 years. How many children were there altogether?

Hi

Total excess above average = Total shortfall below average.

8 x (15-10) = N x (10-6)
N= 10 --> 10 girls, total 10 + 8 = 18 children.

cheers.

[/quote]Both methods are correct. But your friend made calculation error :

(120 + 6G)/(8+G) = 10
120 + 6G = 80 + 8G (wrong)
Should be 120 + 6G = 80 + 10G
40 =4G
G = 10

So, total children = 18.

[thmejlfm]

Ok. Thanks


\"]

thmejlfm:

Hi, thanks for the reply.

One of friends told my dd, was

8 x 15 = 120 (boys total)
G x 6 = 6G (girls total)

120 + 6G/8+G = 10
120 + 6G = 80 + 8G
40 =2G
G = 20

So, total children = 28.

So, which one is correct?

MathIzzzFun:

[quote=\"thmejlfm\"]Please help.

In a group of children, the mean age of the children is 10 years. If the mean age of the 8 boys was 15 years, the mean age of the girls was6 years. How many children were there altogether?

Hi

Total excess above average = Total shortfall below average.

8 x (15-10) = N x (10-6)
N= 10 --> 10 girls, total 10 + 8 = 18 children.

cheers.

[/quote]Both methods are correct. But your friend made calculation error :

(120 + 6G)/(8+G) = 10
120 + 6G = 80 + 8G (wrong)
Should be 120 + 6G = 80 + 10G
40 =4G
G = 10

So, total children = 18.[/quote]

[Bunny27]

Hi, needs help in this sum :


Nassim invited many children to his birthday party. Half of his guests were from the neighborhood. The remaining half was his classmates. The rest were his 10 cousins. How many guests did he invite?

Thanks

ChiefKiasu:

Moderator's Note: Please use this thread to ask for help on specific questions. Please refrain from out of topic chatter in this thread to make it easier for the community to find the answers they need.

[smartmummy]

Bunny27:

Nassim invited many children to his birthday party. Half of his guests were from the neighborhood. The remaining half was his classmates. The rest were his 10 cousins. How many guests did he invite?

http://i53.tinypic.com/23uwox4.jpg\">

remaining half= half of remaining like Asia Dance=Dance of Asia

[Bunny27]

smartmummy:

Bunny27:

Nassim invited many children to his birthday party. Half of his guests were from the neighborhood. The remaining half was his classmates. The rest were his 10 cousins. How many guests did he invite?

http://i53.tinypic.com/23uwox4.jpg\">

remaining half= half of remaining like Asia Dance=Dance of Asia

Thanks thanks!

[millan]

Hi ,

Just one week before my dd 's maths, I just realized that she is using the traditional method of doing multiplication . For eg, 186* 24, we will do 4186 then 20186, but she does by 624+8024+100* 24, mathematically both are correct, qn is am I correct to ask her to change? By doing 2nd method, u need to plus 3 rows and prone to summation mistake but she said she get used to it. Need advice if I shld force her to change. Thks

[millan]

millan:

Hi ,

Just one week before my dd 's maths, I just realized that she is using the traditional method of doing multiplication . For eg, 186* 24, we will do 4*186 then 20*186, but she does by 6*24+80*24+100* 24, mathematically both are correct, qn is am I correct to ask her to change? By doing 2nd method, u need to plus 3 rows and prone to summation mistake but she said she get used to it. Need advice if I shld force her to change. Thks

Sorry I mean not using the old mtd