
By: achieve_goal (offline) Monday, June 17 2013 @ 08:44 PM CDT (Read 1258 times)



achieve_goal 
There are more pupils in School A than School B. 30% of the pupils in School A is 45 more than
40% of the pupils in School B. If 10 % of the pupils in School A leaves to Join School B, there
will be 200 more pupils in School A than School B.
a) How many pupils are there in School B?
b) How many percent less pupils are there in school B than school A?
leave your answer as fraction in the simplest form.

Regular Member
Registered: 09/14/11 Posts: 102





By: echeewh (offline) Monday, June 17 2013 @ 10:26 PM CDT



echeewh 
Hi <achieve_goal>,
Following pls find my worked solution:
<before>
(3/10)A  (4/10)B = 45  (1)
(3/10)A = (4/10)B + 45
(1/10)A = (4/30)B + 15
<after>
B:
1B + (4/30)B + 15 = (34/30)B + 15 = (17/15)B + 15
(9/10)A  (17/15)B  15 = 200
(9/10)A  (17/15)B = 215  (2)
(a)
Using Simultaneous method and eliminate A:
(1)x3:
(9/10)A  (12/10)B = 135  (3)
(2)(3):
(12/10)B  (17/15)B = 80
(6/5)B  (17/15)B = 80
(1/15)B = 80
B = 80 × 15 = 1200
(b)
in (1),
(3/10)A  (4/10)B = 45
(3/10)A = 45 + (4/10)B = 45 + 480 = 525
A = 525 × (10/3) = 1750
%less = [(B  A) / A] × 100
[(1200  1750) / 1750] × 100
=  31 3/7 %
School B has 31 3/7 % less pupils than School A
======
Trust this helps.
Do let me know again if this is different from your <Answerkey> or if there's further clarification.
Cheers,
Edward
P/s. Afraid you are not making much progress with this kind of skill yet.

Active Member
Registered: 04/21/11 Posts: 627





By: achieve_goal (offline) Tuesday, June 18 2013 @ 08:05 PM CDT



achieve_goal 
Hey there,
I do not understand this part :
(2)(3):
(12/10)B  (17/15)B = 80
(6/5)B  (17/15)B = 80
(1/15)B = 80
B = 80 × 15 = 1200
Can you kindly help me with that part?

Regular Member
Registered: 09/14/11 Posts: 102





By: echeewh (offline) Tuesday, June 18 2013 @ 09:45 PM CDT



echeewh 
Hi <achieve_goal>,
Here's the clarification bit :
(2)(3) means taking the difference between the two equations.
(9/10)A  (17/15)B  (9/10)A + (12/10)B = 215  135
(12/10)B  (17/15)B = 80
Simplifying (12/10)B gives (6/5)B, so
(6/5)B  (17/15)B = 80
and I'm very sure you can work out the rest on your own.
=======
Trust this clarifies.
Let me know again if you are in doubt still.
Cheers,
Edward

Active Member
Registered: 04/21/11 Posts: 627





By: achieve_goal (offline) Tuesday, June 18 2013 @ 10:48 PM CDT



achieve_goal 
Thank you for clarifying; I understand better now.

Regular Member
Registered: 09/14/11 Posts: 102



