
By: JessicaTan (offline) Wednesday, August 01 2012 @ 04:34 AM CDT (Read 1005 times)



JessicaTan 
Can someone helps me with the following questions.
1) John saves 30% of his salary is reduced by 10%, his savings is reduced by $90. How much is his original salary?
2) Mrs Lee spent 50% of her monthly salary on food and spent 20% of the remainder on transport every month. If she spent $900 altogether on food and transport a month, how much does she earn in a month?
3) In a class, 40% of the pupils wore glasses. After 4 pupils who wore glasses left the class, the percentage of pupils who wore glasses dropped to 25%. How many pupils in the class did not wear glasses?
Thanks
Jessica

Regular Member
Registered: 10/17/09 Posts: 82





By: echeewh (offline) Wednesday, August 01 2012 @ 10:08 PM CDT



echeewh 
Hi Jessica,
Followig pls find the worked solutions:
Q1
< I have a minor clarification here with regards to the question itself. This is the statement  John saves 30% of his salary is reduced by 10%,. It appears there's some form of typo error here. However, I took it that it reads this way  John saves 30% of his salary. If his salary is reduced by 10%, his savings is reduced by $90. Do let me know if its different as I may need to rework on the solution again.>
Salaries:
original salary (O) = 100% (100u)
current salary (C) = 90% (90u) (since salary reduced by 10%)
Savings:
30% x 100u = 30u (based on Original(O))
30% x 90u = 27u (based on current (C))
Difference in Savings = 3u > $90
1u > 30
Original (O) salary = 100u > 100 x 30 = $3000
============================
Q2
F = 50% of salary (S)
Remainder = 50% S
T = 20% of Remainder = 20% x 50 = 10% S
F + T = 900
50% + 10% = 900
60% = 900
S = 100% = (900/60) x 100 = $1500
=============================
Q3
WG  Without Glasses
<Before>
G : WG
40 : 60
2 : 3
<After>
25 : 75
1 : 3
Apply <Unchanged Qty> concept (i.e. number of pupils without glasses remains unchanged before and after).
From the above ratios <Before> and <After>, number of units for WG remains unchanged; thereby agreeing with the concept.
From G <before> and <after>, number of units decreases from 2u to 1u. So we have ...
1u > 4
Number of pupils WG = 3u > 3 x 4 = 12
=============================
Trust these help.
Do let me know again if these do not match your Answerkeys or if there's any clarification.
Cheers,
Edward

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





By: JessicaTan (offline) Thursday, August 02 2012 @ 09:23 AM CDT



JessicaTan 
Sorry that was typo error in my first question and Thank you so much for your help.
Regs
Jessica

Regular Member
Registered: 10/17/09 Posts: 82



