Q&A - PSLE Math

[MathIzzzFun]

small:

MathIzzzFun:

[quote=\"small\"]Need some advice and thanks in advance.


Question:
There are 42 pupils in each of the classes, Primary 5A and Primary 5B. The ratio of the number of boys in Primary 5A to the number of boys in Primary 5B was 3:4. The ratio of the number of girls in Primary 5A to the number of girls in Primary 5B was 4:3. There were 56 boys altogether in both classes.
What was the ratio of boys in Primary 5A to the number of girls in Primary 5B?
(Given answer is 1:1 but my DS’s answer is 12:5)

Hi small,

The question is ambiguous - 2 possible answers.

1)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

From 5A = B B B G G G G = 42 => G =6
5B = B B B B G G G = 42 => B = 6
So, G = B = 6

Ratio of 5A boys to 5B girls = 1: 1

2)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

Given total number of boys = 56
so 7B = 56, B =8, G=4

5A boys : 5B girls = 3 x 8 : 3 x 4 = 2 : 1

cheers.

Hi MathIzzzFun,

Many thanks for your time. :)[/quote]Hi small,

you are welcome :lol:

cheers.

[MathIzzzFun]

bobsg01:

http://i53.tinypic.com/9px7c7.jpg\">


Answer given was $655

But have problem how it was derived.

Hope after today, the MOE will do some self reflection on S'pore PSLE math. It's really tough for our young child.

Hi bobsg01

hope this helps

http://www.flickr.com/photos/62167097@N02/5697131686/in/photostream

cheers.

[small]

MathIzzzFun:

Need some advice and thanks in advance.


Question:
There are 42 pupils in each of the classes, Primary 5A and Primary 5B. The ratio of the number of boys in Primary 5A to the number of boys in Primary 5B was 3:4. The ratio of the number of girls in Primary 5A to the number of girls in Primary 5B was 4:3. There were 56 boys altogether in both classes.
What was the ratio of boys in Primary 5A to the number of girls in Primary 5B?
(Given answer is 1:1 but my DS’s answer is 12:5)

[quote]Hi small,

The question is ambiguous - 2 possible answers.

2)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

Given total number of boys = 56
so 7B = 56, B =8, G=4

5A boys : 5B girls = 3 x 8 : 3 x 4 = 2 : 1]

cheers.[/quote]
Hi MathIzzzFun,

Sorry, solution 2 looks logical but I think the answer is incorrect.

Given total number of boys = 56
so 7B = 56, B =8, G=4

Base on this, my DS said:
5A = B B B G G G G = 24 + 16 = 40
5B = B B B B G G G = 32 + 12 = 44
:oops:

Can you please help again ? Many thanks in advance.

[MathIzzzFun]

small:

MathIzzzFun:

Need some advice and thanks in advance.


Question:
There are 42 pupils in each of the classes, Primary 5A and Primary 5B. The ratio of the number of boys in Primary 5A to the number of boys in Primary 5B was 3:4. The ratio of the number of girls in Primary 5A to the number of girls in Primary 5B was 4:3. There were 56 boys altogether in both classes.
What was the ratio of boys in Primary 5A to the number of girls in Primary 5B?
(Given answer is 1:1 but my DS’s answer is 12:5)

[quote]Hi small,

The question is ambiguous - 2 possible answers.

2)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

Given total number of boys = 56
so 7B = 56, B =8, G=4

5A boys : 5B girls = 3 x 8 : 3 x 4 = 2 : 1]

cheers.

Hi MathIzzzFun,

Sorry, solution 2 looks logical but I think the answer is incorrect.

Given total number of boys = 56
so 7B = 56, B =8, G=4

Base on this, my DS said:
5A = B B B G G G G = 24 + 16 = 40
5B = B B B B G G G = 32 + 12 = 44
:oops:

Can you please help again ? Many thanks in advance.[/quote]Hi small,

you are right, must be having mid-night blues :lol:

Seems that there is no answer in this case, cos for solution 1, B = G = 6 => Total number of boys = 42 instead of 56.

cheers.

[bobsg01]

Hi MathIzzzFun,


Thanks you.

:boogie: :boogie: :boogie:

[MathIzzzFun]

bobsg01:

Hi MathIzzzFun,


Thanks you.

:boogie: :boogie: :boogie:

hi bobsg01,

avec plaisir :lol:

cheers.

[raghupavithra]

2/3​ of X is equal to 1/5​ of Y. Find the value of 80% of Y if X is 930. how to do this sum

[raghupavithra]

2/3​ of X is equal to 1/5​ of Y. Find the value of 80% of Y if X is 930. how to do this sum

[corneyAmber]

raghupavithra:

2/3​ of X is equal to 1/5​ of Y. Find the value of 80% of Y if X is 930. how to do this sum

Y = 5 x 2/3 X
Y = 10/3 x 930 = 3100

So 80%Y = 0.8 x 3100 = 2480

[pixiedust]

Please help me with these 2 maths questions, much thanks :


(1) Mrs. Tan bought 4 times as many toy guns as teddy bears.
She spent $1750 altogether.
A toy gun cost $10 less than a teddy bear.
The total cost of toy guns was $490 more than the cost of teddy bears.

(a) how much did Mrs. Tan spend on the teddy bears ? [ans: $630, no problem]
(b) how much did one teddy bear cost ? [ans: $18, need help]

(2) Sandra had twice as many apples as oranges as first. She removed 4 apples and 3 oranges each time. In the end, there were 18 apples and 1 orange left. How many fruits did Sandar have at first ? [ans: 75, need help]