give 10sums on comparing quantities.small one
Answers
Answer:
Question 1.
Express the following in decimal form:
(a) 12%
(b) 25%
Solution:
(a) 12% = \frac { 12 }{ 100 } = 0.12
(b) 25% = \frac { 25 }{ 100 } = 0.25
Question 2.
Evaluate the following:
(a) 20% of 400
(b) 12\frac { 1 }{ 2 }% of 625
Solution:
Comparing Quantities NCERT Extra Questions for Class 8 Maths Q2
Question 3.
If 20% of x is 25, then find x.
Solution:
20% of x = 25
Comparing Quantities NCERT Extra Questions for Class 8 Maths Q3
Hence x = 125
Question 4.
Express the following as a fraction
(a) 35%
(b) 64%
Solution:
Comparing Quantities NCERT Extra Questions for Class 8 Maths Q4
Question 5.
Express the following into per cent
(а) 1\frac { 3 }{ 5 }
(b) 2 : 5
Solution:
Comparing Quantities NCERT Extra Questions for Class 8 Maths Q5
Question 6.
There are 24% of boys in a school. If the number of girls is 456, find the total number of students in the school.
Solution:
Let the total number of students be 100.
Number of boys = 24% of 100 = \frac { 24 }{ 100 } × 100 = 24
Number of girls = 100 – 24 = 76
⇒ If number of girls is 76, then total number of students = 100
⇒ If Number of girls is 1, then total number of students = \frac { 100 }{ 76 }
If Number of girls is 456, then total number of students = \frac { 100\times 456 }{ 76 } = 600
Hence, the total number of students in the school = 600
Question 7.
The cost of 15 articles is equal to the selling price of 12 articles. Find the profit per cent.
Solution:
Let CP of 15 articles be ₹ 100
CP of 1 article = ₹ \frac { 100 }{ 15 }
SP of 12 articles = ₹ 100
SP fo 1 article = ₹ \frac { 100 }{ 12 }
SP > CP
Comparing Quantities NCERT Extra Questions for Class 8 Maths Q7
Comparing Quantities NCERT Extra Questions for Class 8 Maths Q7.1
Hence, profit = 25%
Question 8.
An article is marked at ₹ 940. If it is sold for ₹ 799, then find the discount per cent.
Solution:
MP = ₹ 940
SP = ₹ 799
Discount = MP – SP = 940 – 799 = ₹ 141
Comparing Quantities NCERT Extra Questions for Class 8 Maths Q8
Hence, discount = 15%
Question 9.
A watch was bought for ₹ 2,700 including 8% VAT. Find its price before the VAT was added.
Solution:
Cost of watch including VAT = ₹ 2,700
Let the initial cost of the watch be ₹ 100
VAT = 8% of ₹ 100 = ₹ 8
Cost of watch including VAT = ₹ 100 + ₹ 8 = ₹ 108
If cost including VAT is ₹ 108, then its initial cost = ₹ 100
If cost including VAT is ₹ 1, then its initial cost = ₹ \frac { 100 }{ 108 }
If cost including VAT is ₹ 2,700, then its initial cost = ₹ \frac { 100 }{ 108 } × 2700 = ₹ 2500
Hence, the required cost = ₹ 2,500
Question 10.
Find the amount if ₹ 2,000 is invested for 2 years at 4% p.a. compounded annually.
Solution:
Comparing Quantities NCERT Extra Questions for Class 8 Maths Q10
Comparing Quantities NCERT Extra Questions for Class 8 Maths Q10.1