Sign Up!
Login
Welcome to Test-paper.info
Monday, May 29 2017 @ 06:29 AM CDT
 Forum Index >  Test Paper Related >  Primary 5 Matters
 Nanyang ca2 2011 q15
   |  Printable Version
By: parent603 (offline)  Wednesday, September 18 2013 @ 09:06 AM CDT (Read 545 times)  
parent603

Hi,

Pls help to solve this q.

Hanson had some one-dollar coins and some fifty cents coins. The ratio of the no of one dollar coins to the no

of fifty cents coins was 2:5.

Hanson took 140 fifty cents coins to he bank and changed for the same value of one dollar coins.

In the end, the no of one dollar coins to the no of fifty cents coins is 5:2.

Find the value of the fifty cents coins.

Ans $100.

Forum Newbie
Newbie


Registered: 11/07/11
Posts: 14

Profile Email    
   
By: echeewh (offline)  Wednesday, September 18 2013 @ 08:03 PM CDT  
echeewh

Hello <parent603>

Following is my worked solution:

<before>

$1 : 50cts
2 : 5

<process>

50cts: 140 × 50 = 7000
$1: 7000 ÷ 100 = 70

i.e. 140 50cts coins were taken out in exchange for 70 $1 coins that were put in.

$1: + 70
50cts: - 140

<after>

$1 : 50cts
5 : 2

As both number of $1 and 50cts coins changed, we can use the <Changed Qtys> concept and apply the <Cross Multiply> method here..

(2u + 70) / 5 = (5u - 140) / 2
2 × (2u + 70) = 5 × (5u - 140)
4u + 140 = 25u - 700
25u - 4u = 700 + 140
21u --> 840
1u --> 840 ÷ 21 = 40

Hence, number of 50 cts coins (at first)
= 5u --> 5 × 40 = 200
Value: 200 × 50 = 10000 cts = $100

=========

Trust this helps.

Do let me know again if there's further clarifications.

Cheers,
Edward

Forum Active Member
Active Member

Registered: 04/21/11
Posts: 623

Profile Email    
   


 All times are CDT. The time is now 06:29 am.
Normal Topic Normal Topic
Locked Topic Locked Topic
Sticky Topic Sticky Topic
New Post New Post
Sticky Topic w/ New Post Sticky Topic w/ New Post
Locked Topic w/ New Post Locked Topic w/ New Post
View Anonymous Posts 
Able to Post 
HTML Allowed 
Censored Content