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 By: JessicaTan (offline)  Wednesday, August 01 2012 @ 04:34 AM CDT (Read 1035 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

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