Formula: 1 Mark
Steps: 2 Marks
Answer: 1 Mark
Given, Selling price = ₹ 13,500
$Loss\%=20\%$
Let the cost price be $x.$
$\therefore Loss=20\%ofx$
Selling price = Cost price - Loss 
$\Rightarrow 13500=x-\frac{20}{100}\times x$
$\Rightarrow 13500=x-\frac{1}{5}x$
$\Rightarrow 13500=\frac{4}{5}x$
$\Rightarrow x=16875$
Therefore, she bought it for ₹ 16875.
So, cost price of the article = ₹ 16875
20% of the cost price
$=\frac{20}{100}\times 16875=₹3375$
Net amount = 16875 + 3375 = ₹ 20250
So, in order to sell the washing machine at 20% profit, she needs to sell it at ₹ 20250.

Formula: 1 Mark
Steps: 2 Marks
Answer: 1 Mark
Given,
Principal (P) = ₹ 1200
Rate (R) = $12\%$ p.a.
Time (T) = 3 years
$S.I.=\frac{P\times R\times T}{100}$
$S.I.=\frac{1200\times 12\times 3}{100}$
$S.I.=₹432$
Total amount to be paid at the end of three years = P + S.I.
Amount = ₹ 1200 + ₹ 432
Amount = ₹ 1632
₹ 1632 has to be paid at the end of three years.

Formula: 1 Mark
Application: 1 Mark
Steps: 1 Mark
Answer: 1 Mark
Given that,
Population 2 years ago = 62500.
Rate of decrease = 4 % p.a.
For population 1 year ago,
P = 62500 , R = 4 %, T = 1 year
$\therefore S.I=\frac{P\times R\times T}{100}$
$\Rightarrow I=\frac{62500\times 4\times 1}{100}$
$\Rightarrow I=2500$
$\Rightarrow$ After 1 year the population will decrease by 2500 people
$\therefore$ Population 1 year ago is = 62500 - 2500 = 60,000
For present population, 
P = 60,000, R = 4 %, T = 1 year
$\therefore S.I=\frac{P\times R\times T}{100}$
$\Rightarrow I=\frac{60000\times 4\times 1}{100}$
$\Rightarrow I=2400$
$\Rightarrow$ Present population = 60,000 - 2400 = 57,600
[We are subtracting the population because population is decreasing by 4% p.a.]
The present population is 57,600.

Application: 1 Mark 
Steps: 2 Marks
Answer: 1 Mark

Let the cost price of item sold at loss be ₹ x

$\Rightarrow x-10\%ofx=45$

$\Rightarrow x-\frac{10}{100}\times x=45$

$\Rightarrow x-\frac{1}{10}\times x=45$

$\Rightarrow \frac{10x-x}{10}=45$

$\Rightarrow x=50\Rightarrow \text{Cost price is}$  ₹ 50

$\Rightarrow Loss$ =  ₹ (50 - 45) =  ₹ 5

Similarly, let the cost price of an item sold at profit be ₹ y.

$\Rightarrow y+25\%ofy=40$

$\Rightarrow y+\frac{25}{100}\times y=40$

$\Rightarrow y+\frac{1}{4}\times y=40$

$\Rightarrow \frac{4y+y}{4}=40$

$\Rightarrow y=32\Rightarrow \text{Cost price is}$   ₹ 32

$\Rightarrow \text{Profit}$ =  ₹(40 - 32) =  ₹ 8

Net gain =  ₹ (8 - 5) =  ₹ 3
 
So, the shopkeeper makes a profit of  ₹ 3.

For 6 students we need 3 balls.
$\Rightarrow$ For 1 student, we need $\frac{3}{6}=\frac{1}{2}$  balls.
Therefore, 36 students would need:
$36\times \frac{1}{2}=$ 18 balls.

Steps: 1 Mark
Answer: 1 Mark
Given that:
In a city, there are 15000 voters.
60% of the voters voted.
Total percentage of voters = 100%
Voters who voted in % = 60%
$\Rightarrow$ Percentage of voters who did not vote
= 100 - 60 = 40%
Total Voters = 15000
40% of 15000 did not vote.
Then, the number of voters who did not vote is:
= 40% of 15000
$\Rightarrow \frac{40}{100}\times 15000=6000$
$\therefore$ 6000 voters did not vote.

Formula: 1 Mark
Answer: 1 Mark

Given that:
Rashi can travel for 4 hours after having a pizza.
Rashid can travel for 6 hours after having a pizza.
Number of hours Rashid travels more after having a pizza = 6 - 4 = 2 hours
In terms of percentage, it is given by, 

$\frac{\text{Extra hours}}{\text{Number of hours Rashi can travel after having a pizza}}\times 100$

On substituting the values we get,

$\frac{2}{4}\times 100=50$

Units: 1 Mark
Answer: 1 Mark
Given that:
Rashi travelled 6 km.
Soham travelled 5000 m. 
We have to find the ratio of their distance travelled. 
We can only find the ratio if they have the same units.
First, we will convert both the distances to the same unit.
So, $6\text{km}=6\times 1000\text{m}=6000\text{m}$.
Thus, the required ratio is:
 6000 m : 5000 m
$\Rightarrow$ 6:5

Each option: 1 Mark
Given decimal is,
a) 0.65
$=0.65\times 100\%$
$=\frac{65\times 100}{100}\%=65\%$
b) 2.1
$=2.1\times 100\%$
$=\frac{21\times 100}{10}\%=210\%$