
By: KCTAN (offline) Saturday, August 03 2013 @ 03:07 AM CDT (Read 1084 times)



KCTAN 
Hi,
Can anyone help with the following questions? Thank you!
1. Roy had 50 marbles than Jude. Roy gave 60% of his marbles to Jude.
Jude then gave 50% of his marbles to Roy.
In the end, Jude had 160 fewer marbles than Roy.
How many did Roy have at first?
2. There are more pupils in School A then School B.
30% 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 in simplest form.)
(3) In a school hall, chairs were arranged in rows such that there were exactly 9 chairs in each row,
For a concert, Mr Ong brought 6 more chairs into the school hall and rearranged the chairs.
There are now exactly 7 chairs in each row and 12 more rows than before.
How many chairs are there in the school hall for the concert?

Newbie
Registered: 11/02/11 Posts: 9





By: echeewh (offline) Saturday, August 03 2013 @ 09:54 PM CDT



echeewh 
Hey <KCTAN>,
//updated
Q1 completed and posted 5/8/13 , 9am
//
Q1 is still in progress. Noted some missing word(s) in this 1st line ( Roy had 50 marbles than Jude )
As for Q2, pls refer to the solution provided on p6 of this forum (as at 4/8/13) [ Subject: maths , last posted on 18/6/13 ]. Thank you.
Following is my worked solution for Q3:
Q3
<before>
Let number of rows be 1u.
Given that there were 9 chairs in each row,
Total chairs = 9u
<after 6 more chairs added>
Total chairs = 9u + 6  (1)
Number of rows = 1u + 12
Given that there were 7 chairs in each row,
Total chairs = 7 × (1u + 12) = 7u + 84  (2)
Hence, we can equate (1),(2) {i.e. (1) = (2)}
9u + 6 = 7u + 84
9u  7u = 84  6
2u = 78
1u = 39
Number of chairs for the concert
= 9u + 6
= (9 × 39) + 6
= 351 + 6
= 357
==========
Trust this helps.
Do let me know again if this is different from your <Answerkey> or if there's further clarification.
Cheers,
Edward

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





By: echeewh (offline) Sunday, August 04 2013 @ 07:57 PM CDT



echeewh 
Hi there,
Following is the worked solution for Q1.
***  for alignment purpose
Assume the statement is "Roy had 50 marbles more than Jude"
R  J = 50
<after R gave 60% (3/5) to J>
Develop the <before> model as follows:
Split the equal portion of R, J into 5 equal units as shown:
<Before>
R <50> > 5u + 50
J  ******* > 5u
<R gave (3/5) to J>
(3/5)R = (3/5) × (5u + 50)
= 3u + 30
<after>
R: 5u + 50  3u  30 = 2u + 20
J: 5u + 3u + 30 = 8u + 30
<after J gave 50% to R>
50% J = (1/2)J
= (1/2) × (8u + 30)
= 4u + 15
R: 2u + 20 + 4u + 15 = 6u + 35
J: 8u + 30  4u  15 = 4u + 15
Given that J had 160 fewer marbles than R in the end,
R  J = 160
6u + 35  4u  15 = 160
2u + 20 = 160
2u = 160  20 = 140
1u > 140 ÷ 2 = 70
R (at first) = 5u + 50
5u + 50 > (5 × 70) + 50
= 350 + 50
= 400
============

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





By: KCTAN (offline) Sunday, August 04 2013 @ 11:02 PM CDT



KCTAN 
Hi echeewh,
Thank you so much for the explanation.
The answers are correct.
Apologies for the typo, I left out the word "more".
The correct statement is indeed "Roy had 50 marbles more than Jude".
Appreciate your guidance!

Newbie
Registered: 11/02/11 Posts: 9



