Q&A - PSLE Math
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Dharma:
Glad you like it, ksi.[/quote]thanks to both of u...
I like this shorter approach! :imcool:ksi:
[quote=\"Dharma\"]When distance is fixed; speed and time are inversely proportional.
Speed ratio => 80 : 60 = 4 : 3
Time ratio => 3: 4
4u ā 3u = 1u = (3/4 ā 1/3) = 5/12 hrs
Total distance = 80 x 3 x 5/12 = 100km
Time taken when speed is 90km/hr = 100/90 = 10/9 hrs -
Please help.
Paya Lebar Methodist Girls' Prelim Question 15.
http://www.orlesson.org/orp/09Ma/2009-P6-Math-SA2-PLMGS.pdf
The following pattern is created with 4 letters, A, B, C and D.
ABCDAABBCCDDAAABBBCCCDDD.................?
..............................................24th 230th
Following the above pattern, what is the 230th letter?
(1) A
(2) B
(3) C
(4) D
Given answer is (1).
TIA. -
P5G:
HiPlease help.
Paya Lebar Methodist Girls' Prelim Question 15.
http://www.orlesson.org/orp/09Ma/2009-P6-Math-SA2-PLMGS.pdf
The following pattern is created with 4 letters, A, B, C and D.
ABCDAABBCCDDAAABBBCCCDDD.................?
..............................................24th 230th
Following the above pattern, what is the 230th letter?
(1) A
(2) B
(3) C
(4) D
Given answer is (1).
TIA.
The pattern can be grouped as follows:
group 1 (each letter appearing once) = ABCD
group 2 (each letter appearing twice) = AABBCCDD
and so forth
The total number of letters in each group will then be 4x1, 4x2, 4x3 etc..
To find the 230th letter, divide 230 by 4 = 57.5, so we need to find the group number n such that 1+2+3+4+...n is less than or equal to 57.5
1+2+3+4+5...+10 = 55
So, we know that 230th letter will be in group 11 ie each letter appearing 11 times,
4 x 55 = 220 (total number of letters in group 1 to group 10), 230 - 220 = 10, since A is the first letter, and each letter appears 11 times, the 10th letter in group 11 or the 230th letter is an \"A\"
cheers. -
Hi,
Can someone help in this question from Raffles Girls'Prm Sch-Prelim-Q18. TIA
There are more pupils in Sch A than Sch B.
30% of the pupils in Sch A is 45 more than 40% of the pupils in Sch B.
If 10% of the pupils in Sch A leaves to join Sch B, there will be 200 more pupils in Sch A than Sch B.
a) How many pupils are there in Sch B?
b) How many percent less pupils are there in Sch B than Sch A?
Leave your answer as fraction in the simplest form. -
Hi fxchow,
HTH but I am not so sure on my answer for part (b).
a)
Given that 30% of the pupils in Sch A is 45 more than 40% of the pupils in Sch B.
0.3A - 45 = 0.4B --> x10
3A = 4B + 450 ----- equation (1)
If 10% of the pupils in Sch A leaves to join Sch B, there will be 200 more pupils in Sch A than Sch B
0.9A ā 200 = 0.1A + 1B
0.8A = 1B + 200 --> x10
8A = 10B + 2000 ----- equation (2)
We will need to eliminate A to get B;
equation (1) x 8:
24A = 32B + 3600
equation (2) x 3:
24A = 30B + 6000
32B + 3600 = 30B + 6000
2B ā 6000 ā 3600
2B = 2400
1B = 1200
There are 1200 pupils in Sch B
b)
from equation (1) :
3A = 4 X 1200 + 450
3A = 4800 + 450
3A = 5250
1A = 1750 (100%)
The different between School A and School B is:
1750 ā 1200 = 550
1750 = 100%
550 = 550/1750 x 100%
= 1100 / 35 %
= 31 3/7%
There are 31 3/7% percent less pupils in Sch B than Sch A -
fxchow:
hi fxchow,Hi,
Can someone help in this question from Raffles Girls'Prm Sch-Prelim-Q18. TIA
There are more pupils in Sch A than Sch B.
30% of the pupils in Sch A is 45 more than 40% of the pupils in Sch B.
If 10% of the pupils in Sch A leaves to join Sch B, there will be 200 more pupils in Sch A than Sch B.
a) How many pupils are there in Sch B?
b) How many percent less pupils are there in Sch B than Sch A?
Leave your answer as fraction in the simplest form.
hope this helps
http://www.flickr.com/photos/62167097@N02/5842021695/in/photostream
cheers. -
small:
Hi Small,Hi fxchow,
HTH but I am not so sure on my answer for part (b).
a)
Given that 30% of the pupils in Sch A is 45 more than 40% of the pupils in Sch B.
0.3A - 45 = 0.4B --> x10
3A = 4B + 450 ----- equation (1)
If 10% of the pupils in Sch A leaves to join Sch B, there will be 200 more pupils in Sch A than Sch B
0.9A ā 200 = 0.1A + 1B
0.8A = 1B + 200 --> x10
8A = 10B + 2000 ----- equation (2)
We will need to eliminate A to get B;
equation (1) x 8:
24A = 32B + 3600
equation (2) x 3:
24A = 30B + 6000
32B + 3600 = 30B + 6000
2B ā 6000 ā 3600
2B = 2400
1B = 1200
There are 1200 pupils in Sch B
b)
from equation (1) :
3A = 4 X 1200 + 450
3A = 4800 + 450
3A = 5250
1A = 1750 (100%)
The different between School A and School B is:
1750 ā 1200 = 550
1750 = 100%
550 = 550/1750 x 100%
= 1100 / 35 %
= 31 3/7%
There are 31 3/7% percent less pupils in Sch B than Sch A
Thank you for your solution, your answer b is correct.
-
MathIzzzFun:
hi fxchow,fxchow:
Hi,
Can someone help in this question from Raffles Girls'Prm Sch-Prelim-Q18. TIA
There are more pupils in Sch A than Sch B.
30% of the pupils in Sch A is 45 more than 40% of the pupils in Sch B.
If 10% of the pupils in Sch A leaves to join Sch B, there will be 200 more pupils in Sch A than Sch B.
a) How many pupils are there in Sch B?
b) How many percent less pupils are there in Sch B than Sch A?
Leave your answer as fraction in the simplest form.
hope this helps
http://www.flickr.com/photos/62167097@N02/5842021695/in/photostream
cheers.
Hi MathIzzzFun,
Thank you for your model drawing, it's great.
fxchow -
fxchow:
hi fxchow,MathIzzzFun:
[quote=\"fxchow\"]Hi,
Can someone help in this question from Raffles Girls'Prm Sch-Prelim-Q18. TIA
There are more pupils in Sch A than Sch B.
30% of the pupils in Sch A is 45 more than 40% of the pupils in Sch B.
If 10% of the pupils in Sch A leaves to join Sch B, there will be 200 more pupils in Sch A than Sch B.
a) How many pupils are there in Sch B?
b) How many percent less pupils are there in Sch B than Sch A?
Leave your answer as fraction in the simplest form.
hope this helps
http://www.flickr.com/photos/62167097@N02/5842021695/in/photostream
cheers.
Hi MathIzzzFun,
Thank you for your model drawing, it's great.
fxchow[/quote]u r welcome
cheers. -
ksi:
![](\"http://i54.tinypic.com/xprbkl.jpg\")
http://i54.tinypic.com/xprbkl.jpg\">
thanks KSi
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