Exercise 2.3 - Chapter 2 Percentage and Simple Interest Term 3 7th Maths Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

Updated By SaraNextGen

On April 24, 2024, 11:35 AM

$\operatorname{Ex} 2.3$
Question 1.
14 out of the 70 magazines at the bookstore are comedy magazines. What percentage of the magazines at the bookstore are comedy magazines?
Solution:
Total number of magazines in the bookstore $=100 \mathrm{~m}$
Number of comedy magazines $=14$
Percentage of comedy magzines $=\frac{14}{70} \times 100 \%=20 \%$
$20 \%$ of the magazines are comedy magazines.
 

Question $2 .$
A tank can hold 50 litres of water. At present, it is only $30 \%$ full. How many litres of water will fill the tank, so that it is $50 \%$ full?
Solution:
Capacity of the $\operatorname{tank}=50$ litres
Amount of water filled $=30 \%$ of 50 litres $=\frac{30}{100} \times 50=15$ litres
Amount of water to be filled $=50-15=35$ litres
 

Question $3 .$
Karun bought a pair of shoes at a sale of $25 \%$. If the amount he paid was $₹ 1000$, then find the marked price.
Solution:
Let the marked price of the raincoat be $₹ \mathrm{P}$
Amount he paid at a discount of $25 \%=₹ 1000$
(Marked Price) $-(25 \%$ of P $)=1000$
$\begin{aligned}
&\mathrm{P}-\left(\frac{25}{100} \times \mathrm{P}\right)=1000 \\
&\mathrm{P}-\frac{1}{4} \times \mathrm{P}=1000
\end{aligned}$

$\begin{aligned}
&P\left(1-\frac{1}{4}\right)=1000 \\
&\frac{3}{4} P=1000 \\
&P=1000 \times \frac{4}{3} \\
&=\frac{4000}{3} \\
&P=1333.33
\end{aligned}$
$\therefore$ Marked price of the shoes $=₹ 1333$

Question $4 .$
An agent of an insurance company gets a commission of $5 \%$ on the basic premium he collects. What will be the commission earned by him if he collects ₹ 4800 ?
Solution:
Premium collected $=₹ 4800$
Commission earned $=5 \%$ of basic premium
Commission earned for $₹ 4800=5 \%$ of 4800
$\begin{aligned}
&=\frac{5}{100} \times 4800 \\
&=₹ 240
\end{aligned}$
Commission carned $=₹ 240$
 

Question $5 .$
A biology class examined some flowers in a local Grass land. Out of the 40 flowers they saw, 30 were perennials. What percentage of the flowers were perennials?
Solution:
Number of flowers examined $=40$
Number of perennials $=30$
Percentage $=\frac{30}{40} \times 100 \%$
$=75 \%$
$75 \%$ of the flowers were perennials.
 

Question $6 .$
Ismail ordered a collection of beads. He received 50 beads in all. Out of that 15 beads were brown. Find the percentage of brown beads?
Solution:

Number of beads received $=50$
Number of brown beads $=5$
Percentage of brown beads $=\frac{15}{50} \times 100 \%$
$=10 \%$
$10 \%$ of the beads was brown
 

Question 7.
Ramu scored 20 out of 25 marks in English, 30 out of 40 marks in Science and 68 out of 80 marks in mathematics. In which subject his percentage of marks is best?
Solution:
Ramu's score in English $=20$ out of 25
Percentage scored in English $=\frac{20}{25} \times 100 \%=80 \%$
Ramu's Score in Science $=30$ out of 40
Percentage scored in Science $=\frac{30}{40} \times 100 \%=75 \%$
Ramu's score in Mathematics $=68$ out of 80
Percentage scored in Maths $=\frac{68}{80} \times 100 \%=85 \%$
$85 \%>80 \%>75 \%$.
$\therefore$ In Mathematics his percentage of marks is the best.

Question $8 .$
Peter requires $50 \%$ to pass. If he gets 280 marks and falls short by 20 marks, what would have been the maximum marks of the exam?
Solution:

Peters score $=280$ marks
Marks needed for a pass $=20$
$\therefore$ Total marks required to get a pass $=280+20=300$
i.e. $50 \%$ of total marks $=300$
$\frac{50}{100} \times$ Total marks $=300$
$\frac{1}{2} \times$ Total Marks $=300$
Total Marks $=300 \times 2=600$
Total marks of the exam $=600$
 

Question $9 .$
Kayal scored 225 marks out of 500 in revision test 1 and 265 out of 500 marks in revision test $2 .$
Find the percentage of increase in her score.
Solution:
Marks scored in revision $\mathrm{I}=225$
Marks scored in revision II $=265$
Change in marks $=265-225=40$
Percentage of increase $=\frac{\text { Change in marks }}{\text { Original marks }} \times 100=\frac{40}{500} \times 100=8 \%$
Percentage of increase in marks $=8 \%$
 

Question $10 .$
Roja earned ₹ 18,000 per month. She utilized her salary in the ratio $2: 1: 3$ for education, savings and other expenses respectively. Express her usage of income in percentage.
Solution:
Amount of Salary $=₹ 18,000$

(i) Total number of parts of salary $=2+1+3=6$
Salary is divided into 3 portions as $\frac{2}{6}, \frac{1}{6}$ and $\frac{3}{6}$
Portion of salary used for education $=\frac{2}{6}$
Salary used for education $=\frac{2}{6} \times 18,000=₹ 6,000$
Percentage for Education $=\frac{6000}{18000} \times 100=33.33 \%$
(ii) Usage of salary for savings $=\frac{1}{6} \times 18,000=₹ 3,000$
Percentage for savings $=\frac{3000}{18000} \times 100=16.67 \%$
(iii) Usage of salary for other expenses $=\frac{3}{6} \times 18,000=₹ 9,000$
Percentage for other expenses $=\frac{9000}{18000} \times 100=50 \%$