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May 07, 2012

Problems on Percentages

37 comments

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Lets do some problems on Percentages  




  • A's income is 20% more than that of B while B's income is 20% less than that of C. Whose income is the highest amongst all?


  •  Sol : Let the income of C be Rs. 100/-


                So, The income of B is Rs. 80/-

                A's income is 20% more than B = (120/100) X 80 = Rs. 96/-

               So, obviously C's income is Highest


    • A's income exceeds that of B's by Rs.600 while B's income is 20% less than that of C's. If total income of all of them put together is Rs. 3.850, what is the income of C ?
          Sol : Let the income of C be Rs. X

                  B's income is 20% less than C's

                  So, B's income is 80% of  X  = 4 X  / 5

                  So, A's income is (4 X /5) + 600 

                       =>  ((4 X /5)+600) + (4 X /5) +  X  = 3,850

                        => (8 X  / 5) +  X  = 3,250

                           =>  13  X  = 5 x 3,250

                                       X  = (5 x 3,250) / 13 = Rs. 1,250

    • Shivani spends 15% of her salary on Shopping, 20% on House - Rent, 50 % on Food and the remaining on Education of Her children. If education costs her Rs 3000, how much does she spend on House - Rent ? 
             Sol :  Let the salary of Shivani is Rs. 100
                       So, amount spent on Education = 100 - ( 15 + 20 + 50) = Rs. 15

                        But, her expences towards education is Rs. 3000

                         So, 15% of salary = (3000 x 100) / 15  = Rs. 20,000

                         She spent 20% of her salary on house rent
                                  So, 20% of 20,000 = Rs. 4000/-
    • In a class, 30% students passed in Maths, 50% students passed in English and 10% students passed in Both. What per cent of students failed in both of these subjects?
            Sol : Let the number of total students = 100
                     So, Number of students passed in Maths = 30
                            Number of students passed in English = 50
                            Number of students passed in Maths and English = 10

                       So, total number of students passed = (30 + 50 - 10) = 70
                             
                             Number of students failed = 30
                   
                          So,     Percentage of Students failed = 30 %


    • A trader announced 10% reduction in the unit price of an article. As a result, the sales volume went up by 10%. What was the net effect on the sales revenue?
              Sol : Let the unit price be Rs. 10/-
                       Let the number of articles sold = 10

                        So, the sales revenue = 10 x 10 = Rs. 100

                        The trader has reduced the unit price by 10%

                        So, Reduced price = 90% of Rs 10 = Rs. 9 /-
                                  and, increase in the sales volume = 10%
                                              = 110% of 10 = 11

                              So, The net effect = 9 x 11 = Rs. 99

                                  The sales revenue has come down by Re. 1/-

                            So, the sales revenue has come down by 1%

            Note : There is a short cut for these type of problems.

                        If price is reduced by X% and sales increase by Y%, the total effect on sales revenue :

                   =      increased % value - Decreased % value = (Increased % value x Decreased % value) / 100

                    The effect on revenue is increased or decreased according to the positive or negative sign otained
                           =  10 - 10 - ((10 x 10) / 10)) = 0 - 1 = -1

                    The sign obtained is negative. Thus, the total revenue decreases by 1%                          
                                                
                                                                                                              

    37 comments:

    1. Mam I have a ques. When I worked it for the 1st time it was correct but now its wrong. ITS :-
      *X spends 20% of his salary on food, 15% on conveyance, 10% on education and 35% on house rent. If he spends Rs.1950 on education, how much does he spend on conveyance?
      Here 100-(10+15+20+35)=Rs.20$
      So, 20%(Rs. 20$ answer) = 1950*100/20 = 9750
      And 15% of salary (Conveyance) = 9750*15/100 = 1462.5
      But answer is 2925.
      1st I got it right when I took 10 instead of 20 (100-80), but how mam? 20 is the remaining of 100. Its correct with 10.
      What should I do?
      Is 20 the remaining of 100 or should I take 10% on education value for 1st factor?

      ReplyDelete
      Replies
      1. ya you should take 10 % because he spend 10 % on Education

        Delete
      2. 1950*100/10=19500
        15% of conveyance :19500*15/100=2925

        Delete
      3. 10% on Eductation
        Total salary 19500/-
        So On con 19500X15/100= 2925

        Delete
    2. very helpful................

      ReplyDelete
    3. it's very useful for me

      ReplyDelete
    4. it is very useful.. great work...

      ReplyDelete
    5. Very helpful than for providing such a useful
      site

      ReplyDelete
    6. Good for non coaching candidate only

      ReplyDelete
    7. is there any shortcut for doing sums like :
      40% of 1740 +X=38% of980 +150 % of 850

      ReplyDelete
    8. Its very us full for all exams

      ReplyDelete
    9. It is very use full for all exams

      ReplyDelete
    10. pls explain the logic of question related to class.

      ReplyDelete
    11. please explain last sum

      ReplyDelete
    12. Please help me to solve this question with short method?

      Mr. Jones gave 40% of the money he had to his wife. He also gave 20% of the remaining amount to each of his three sons. Half of the amount now left was spent on miscellaneous items and the remaining amount of Rs. 12,000 was deposited in the bank. How much money did Mr. Jones have initially?

      ReplyDelete
      Replies
      1. the ans should be 25000.
        the equation goes like this, let the total amt be x, therefore,
        x=40/100(x) + 20/100(x-(40/100(x))) + 12000
        solving for x we get 25000 as the final ans...
        Ma'am please let me know if this approach is wrong.

        Delete
      2. hi frnd,

        i think the ans is 60000

        see he gave 40 % to his wife
        20 % to sons
        in the balance 40% half of the amount goes to miscellaneous i.e., 20 % goes to miscellaneous.
        Now he have 20% balance in bank = 12000

        add all the stuffs
        40%(WIFE)+20%(sons)+20%(mis)+20%(savings = 12000)= 60000

        pls verify.. else explain ur views

        Delete
      3. hi frnd,

        i think the ans is 60000

        see he gave 40 % to his wife
        20 % to sons
        in the balance 40% half of the amount goes to miscellaneous i.e., 20 % goes to miscellaneous.
        Now he have 20% balance in bank = 12000

        add all the stuffs
        40%(WIFE)+20%(sons)+20%(mis)+20%(savings = 12000)= 60000

        pls verify.. else explain ur views

        Delete
      4. 12000*100*100*100/60*80*50 = 50000

        Ans: 50000

        Delete
    13. 100-40=60
      60*20%=12 now 12*3=36
      60-36=24
      24*1/2=12now
      12=12000 then 100=100000

      ReplyDelete
    14. first example is not clear,
      the ans must b A and C both have equal salary.

      ReplyDelete
    15. to whom salary we assume 100 between d given ppl??

      ReplyDelete
    16. TO WHOM SALARY WE CAN ASSUME 100?? BETWEEN D GIVEN PPL

      ReplyDelete
      Replies
      1. (12000*100)/20=60000
        So the answer is 60000

        Delete
    17. its been very helpful for me. thank you

      ReplyDelete

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