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Percentage

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what is the percentage change in perimeter if the length is increased by 20% and breadth is increased by 30%?

aniket prajapati 19/11/2018 2:32 pm
This post was modified 6 years ago 2 times by aniket prajapati

Let length =10  Width = 10

P= 40

Now length = 12 bredth = 13

P' = 50

So percentage increase =(10/40)*100= 25%

TG Team 19/11/2018 2:33 pm

Let the original length of the rectangle be : L 

and the  breadth be B 

Original Area: LB 

Length is increased by 20% so new length : 120L/100 = 6L/5 

Breadth is increased by 30% so new breadth : 130L/100 = 13L/10 

New area : 6L/5 x 13B/10 = 78LB/50 = 39LB/25

% increase = (39-25)/25 x 100= 56%

aniket prajapati 19/11/2018 2:38 pm

Alternatively 

Percentage increase will be the average of percentage increase in sides if perimeter is asked i.e (20+30)/2 = 25%

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where is the answer key of percentage assignment?

TG Team 19/11/2018 2:27 pm

Check the notes section of TG's  facebook page. 

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OUT OF TOTAL, 93.75% OF THE STUDENTS PASSED IN AN EXAMINATION. Find Minimum number of total students?

TG Team 18/01/2019 12:46 pm

Let the total number of students be x. 

So, 93.75% of x is an integer. 

93.75% of x = 15/16 of x . 

Smallest possible value of x  for which 15/16 of x is an integer is 16. 

Hence minimum possible number of students = 16. 

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 A reduction of 20% in the price of eggs would enable a man to obtain 56 more for Rs. 10. what is the original price per dozen of eggs ?

Gaurav Jain 09/03/2019 10:45 am

20% reduction = 80% cost = 4/5 cost

so this would enable him to purchase 5/4 quantity  = 125% quantity = 25% more quantity

25% = 56

100% = 224 (at Rs 10) 

hence intial price of 224 eggs is 10

per dozen cost = (10/224)*12 = 120/224 = 15/28

 

 

 

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The difference in compound interests earned on a certain sum, for which the interest is compounded annually, in the first and the second year is Rs 140. If the rate of interest becomes thrice the original rate, then the difference in the amount (in Rs) would be

Gaurav Jain 02/07/2019 4:05 pm

1st year SI = PR CI= PR
2nd year SI = PR CI = PR+PR^2

Hence difference is PR^2
now if R is triples means 3R
so now difference is P(3R)^2 = 9PR^2 = 9 times

so difference now is 9*140 = 1260

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Comprehensive strength of a cement is a multiple of amount of materials C, S A , F used. If the amount of materials of C, S , A , F are changed by +30%, -30%, -25%, +25% respectively, what will be the overall change in tensile strength of the cement? 

1. no change  2. +14.68%  3.-14.68%  4. Depends on the initial value of a,b,c,d 

Gaurav Jain 02/07/2019 3:59 pm

Strength (S) =K* CSAF
new strength = k*1.3*0.7*1.25*.75 CSAF = 0.8532 k*CSAF = 85.32% original
Hence reduction of 14.68%

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Ram deposits Rs P with a bank at r% compound interest and see it reach Rs 16 P in 20 years. If he had invested the same amount at r% simple interest for 20 years, what would be the amount? 

1. Between Rs 2p and 2.5p

2. between rs 2.5p and 3p

3. between 3p and 3.5p

4. between 3.5p and 4p

This post was modified 5 years ago by tanvi
Gaurav Jain 02/07/2019 2:58 pm

16p in 20 years means,

(1+r)^20 = 16
so (1+r)^5 = 2
from here r is approx = 15% (just less than 15%)

hence in 20 years Amount in simple interest will be = p(1+(20)*.15) = 4p (just less than 4p)

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In the country of Mayapuri, a person pays numerically the same percent in income tax as he makes in Mayapuri Rupees per month. Then, the maximum amount of money in Mayapuri Rupees that a person can take home after paying taxes each month is
A. 20
B. 25
C. 50
D. 60

Gaurav Jain 23/07/2019 4:02 pm

x-x^2/100 = maximum
this is equation of parabola
maximum value will occure at -b/2a
b= 1, a=-1/100
so at x= -1/(-2/100) = 50

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Out of total, 22.1875% students absent on an examination day. find minimum number of total students appeared in an examination?

Gaurav Jain 23/07/2019 1:35 pm

(22.1875/100)*x = integer (because number of absent students should be an integer value

221875/100*10000)*x = integer
71/320)*x = integer
hence minimum value of x = 320
hence absent = 71
present = 320-71

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Hello Sir,

Please provide answer key of percentage module. The ans key on FB Notes page is old and non updated.

 

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A rectangle has distinct dimensions where length is greater than breadth. Length of rectangle is increased by 20% and breadth of rectangle is increased by 30%. What could be the percentage increased in its perimeter? 

Gaurav Jain 16/11/2019 9:08 am

Anything less than 25%
because when length and width are equal then it is 25%. In all the other cases length, which is bigger side has only 20% where has width has 30%. Hence average will shift towards length

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Neraj (Tg)Faculty 10/06/2024 2:23 pm
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The reduction of 15% in the price of salt enables a person to buy 2 kg more for Rs. 272. The reduced price of salt per kg (in Rs.) is :
(a) 22.16 (b) 24.25 (c) 20.40 (d) 25.00

Neraj (Tg)Faculty 10/06/2024 2:24 pm
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Saurabh spends 20% of his monthly income on the education of his children. He spends 30% of the remaining on coveyance and clothes. Further, he spends 50% of the amount still with him on rent and maintenance of the house. After all the expenditure, he sends 50% of the amount still with him to his parents. He saves the remaining Rs. 11,200.

What is his monthly income?

  • 86,000
  • 11,200
  • 1,00,000
  • Rs. 80,000

 

Neraj (Tg)Faculty 10/06/2024 2:18 pm

@neha-singh 

Let the entire salary = 100%

Education expenditure = 20%

Conveyance and clothes expenditure = (100 - 20) × 30% = 24%

Rent and maintenance of the house = (100 – 20 - 24) × 50% = 28%

Remaining = 100 – 20 – 24 – 28 = 28%

Percentage sent to his parents = 28 × 50% = 14%
Remaining with him = 28 – 14 = 14%

According to question,

14% of the income = 11200

So, his total income = 80,000

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