Percentage Questions and Answers

A : B = 80 : 100 = 4 : 5

B : C = 90 : 100 = 9 : 10

If  A : C  = 4 $times$ 9 : 5 $times$ 10 = 36 : 50 = 18 : 25

If B gets Rs. 25, A gets Rs. 18

But C gets 180, then A gets

Rs. $frac{18}{25} times 180$ = Rs. 129.60

Population after 3 years

$= 64000 Big(1 + frac{10}{100}Big)^3 = 64000 times frac{1331}{1000}$

Increase = 64000 $times frac{1331}{1000} - 64000$ = 21184

Let cost price = Rs. 100 per kg
= Rs. 100 per 1000 gm
and he use 1 kg as 800 gm.
 $therefore$  His gain = cost of 200 gm = Rs. 20
 $therefore$ His gain  $\mathrm{\%}=\frac{20}{80}\times 100=25\mathrm{\%}$

Let the side of the square = 100

$therefore text{area } = (100)^2 = 10000$

Due to error, the side of the square = 102
then area =  $(102)^2 = 10404$

$therefore$ difference = 404

$\therefore$ Error % in the area of the square

$= frac{404}{10000} times 100 = 4.04$

Student failed in both subjects = (40 + 30)%
and student failed is at least one subject = (70 - 10)% = 60%
$therefore$ Student passed in both subject = (100 - 60)% = 40%