Percentage

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# Percentage

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Topic starter

During an election 70% of the people who polled said that they would vote for Mr. X Of those who said that, only 60% actually voted for X. Out of those who did not say they would vote for Mr. X, 70% actually voted for X. What percent of those who polled did vote for X?

• a.66%
• b.42%
• c.74%
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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

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

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 4 years ago by tanvi

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

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?

(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?

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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