Q&A - PSLE Math

[MathIzzzFun]

mummyv:

Pls help w this St Nicks CA1 2012, thanks http://i45.tinypic.com/35a4v7p.jpg\">

this was discussed at http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=8610

cheers.

[ngl2010]

I think you'd better post these questions on \"Q&A - PSLE Math\" thread. There are people that regularly help solving Maths problems in that thread. I do not see some of them in other threads so maybe they just zoom in into that thread to help solve Maths problems and do not visit other threads.


And please make sure you don't post any file upside down

[tianzhu]

iamproudparents:

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

Hi

Area formed four right angle triangles ------- 96

Area formed by small square ------- 4 (2*2)

Area of big square WXYZ ------ 100

Length of YZ ------- 10

Best wishes

[tianzhu]

Mum1113:

As no guided answer was provided, my son got his answer: $17.50 .
what's the correct answer?

Hi

Based on the question as crafted, the answer is 18 2/3 which is not a logical one.

Perhaps, the numbers or wordings in the question may not be right.

Please clarify with your teacher.

Best wishes

[tianzhu]

iamproudparents:

http://i47.tinypic.com/1621qpk.jpg\">

Hi

At first
GF ------- 12 units
AF -------- 8 units

In the end
GF ------- 3 units
AF -------- 2 units

Number of fishes removed --------- 15 units -------- 150
1 unit ------- 10

Number of GF removed ------- 9 units -------- 90

Number of AF@first -------- 8 units -------- 80

Best wishes

[jieheng]

iamproudparents:

http://i47.tinypic.com/1621qpk.jpg\">

G 60u (60%)
A 40u (40%)

Also can use G --> 12u (60%) and A --> 8u (40%)

No of goldfish decreased by 75% , 75% of 60u --> 45u

No of angelfish was 1/4 of the original no of angelfish --> no of angelfish decreased by 3/4 --> 3/4 of 40u --> 30 u

total 150 fish were removed

45u + 30u --> 150
75u --> 150
1u --> 2

a)

No of goldfish were removed = 45u = 45*2 = 90

b)

No of angelfish were there at first = 40u = 40*2 = 80

[jieheng]

iamproudparents:

http://i45.tinypic.com/zlt204.jpg\">

B 5u
A 15u

After Anthony spent 1/3 of his money , he left 2/3
2/3 of 15u --> 10u

After Bill spent 3/5 of his money , he left 2/5
2/5 of 5u --> 2u

Anthoy had $130 more than Bill

10u - 2u --> 130
8u --> 130
1u --> 16.25

a)

5u--> 5*16.25 = 81.25
the money that Bill had at first = $81.25

b)

10u --> 10*16.25 = 162.5
the money that Anthony had left = $162.50

[jieheng]

iamproudparents:

http://i47.tinypic.com/24cejcm.jpg\">

B:C:D = 2:3:3

Bond received 1/6 of the total amount of sweets
2/12 (1/6) --> 2u

3/12 -->3u

B+C+D = 2/12 + 3/12 + 3/12 = 8/12

A = 1 - (B+C+D) = 1 - 8/12 = 4/12

Amos took 28 sweets for himself

4u --> 28
1u --> 7

12u --> 12*7 = 84

No of sweets were there in the bag at first = 84

[moonsun]

MathIzzzFun:

moonsun:

Hello.


Would be thankful if someone can teach me how I can solve this...

If 1/5 = 1/A + 1/B and A & B are whole numbers, what are the values of A & B?

1/5 = 1/5 - 1/6 + 1/6 = 1/30 + 1/6

cheers.

Hi Mathizzzfun,

Thank you for the workings.

But.... Sorry, how did you get 1/5-1/6 + 1/6?.... :nailbite:

[MathIzzzFun]

moonsun:

MathIzzzFun:

[quote=\"moonsun\"]Hello.


Would be thankful if someone can teach me how I can solve this...

If 1/5 = 1/A + 1/B and A & B are whole numbers, what are the values of A & B?

1/5 = 1/5 - 1/6 + 1/6 = 1/30 + 1/6

cheers.

Hi Mathizzzfun,

Thank you for the workings.

But.... Sorry, how did you get 1/5-1/6 + 1/6?.... :nailbite:[/quote]this is a common \"trick\" taught to MO students to solve questions like :
1/2 ( 1 + 1/3 +1/6 + 1/10 + 1/15......+1/5050)

cheers.