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Monday, 27 January 2014
Sunday, 26 January 2014
CBSE Class 10 - Maths - CH 14 - Statistics (Ex 14.1)
Statistics
(NCERT Ex 14.1)
Q1: A survey was conducted by a group of students as a part of their environment awareness programme, in which they collected the following data regarding the number of plants in 20 houses in a locality. Find the mean number of plants per house.Answer:
We use the following relation to find the class mark (xi) for each interval:
Class mark (xi) =

Calculating xi and fixi as follows:
| Number of plants | Number of houses(fi) | xi | fixi |
| 0 -2 | 1 | 1 | 1 ☓ 1 = 1 |
| 2 -4 | 2 | 3 | 2 ☓ 3 = 6 |
| 4 -6 | 1 | 5 | 1 ☓ 5 = 5 |
| 6 -8 | 5 | 7 | 5 ☓ 7 = 35 |
| 8 - 10 | 6 | 9 | 6 ☓ 9 = 54 |
| 10 -12 | 2 | 11 | 2 ☓ 11 = 22 |
| 12 - 14 | 3 | 13 | 3 ☓ 13 = 39 |
| Total | 20 | 162 |
From the table, it is observed that
Σ fi = 20
Σ fixi = 162
Mean , x =

=
Therefore, mean number of plants per house is 8.1.
Here, direct method has been used as the values of class marks (xi) and fi are small.
Q2: Consider the following distribution of daily wages of 50 worker of a factory.
| Daily wages(in Rs) | 100 - 120 | 120 - 140 | 140 - 160 | 160 - 180 | 180 - 200 |
| Number of workers | 12 | 14 | 8 | 6 | 10 |
Find the mean daily wages of the workers of the factory by using an appropriate method.
Answer:
Wednesday, 22 January 2014
CBSE Class 10 - Political Science - CH6 Political Parties
Q & As
Q1: What is a political party?
Answer: A political party is a group of people who come together and participate in political campaigns, contest elections, form and run governments by holding power in the government.
Q2: What are the components of a political party?
Answer: A political party has following three components:
- the leader
- active members
- followers
Q3: State the various functions political parties perform in a democracy?
Answer: Main functions performed by a political party are:
- It agrees collectively on various social policies and promote its programmes.
- It seeks to implement these policies by winning public support through political campaigns.
- It participates and contest elections.
- It plays a decisive role in law making.
- It plays a role of opposition and exercise check on the government (or ruling party).
Sunday, 12 January 2014
CBSE Class 8 - Maths - CH 6 - Square and Square Roots (Ex 6.4)
Square and Square roots
Exercise 6.4
(i)2304 (ii) 4489 (iii)3481 (iv) 529 (v)3249 (vi) 1369
(vii)5776 (viii) 7921 (ix)576 (x) 1024 (xi)3136 (xii) 900
Answer:
(i)The square root of 2304 is calculated as follows.
| 48 | |
| 4 | 23 04 -16 |
| 88 | 704 704 |
| 0 |
∴√ 2304 = 48
(ii)The square root of 4489 is calculated as follows.
| 67 | |
| 6 | 44 89 -36 |
| 127 | 889 889 |
| 0 |
∴√ 4489 = 67
(iii)The square root of 3481 is calculated as follows.
| 59 | |
| 5 | 34 81 -25 |
| 109 | 981 981 |
| 0 |
∴√ 3481 = 59
(iv)The square root of 529 is calculated as follows.
| 23 | |
| 5 | 5 29 -4 |
| 43 | 129 129 |
| 0 |
∴√ 529 = 23
(v)The square root of 3249 is calculated as follows.
| 57 | |
| 5 | 32 49 -25 |
| 107 | 749 749 |
| 0 |
∴√ 3249 = 57
(vi)The square root of 1369 is calculated as follows.
| 37 | |
| 3 | 13 69 -9 |
| 67 | 469 469 |
| 0 |
∴√ 1369 = 37
(vii)The square root of 5776 is calculated as follows.
| 76 | |
| 7 | 57 76 -49 |
| 146 | 876 876 |
| 0 |
∴√ 5776 = 76
Saturday, 4 January 2014
CBSE Class 8 - Maths - Cube and Cube Roots (Ex 7.1)
Cube and Cube Roots
(NCERT Ex 7.1)
Q1: Which of the following numbers are not perfect cubes?
(i) 216
(ii) 128
(iii) 1000
(iv) 100
(v) 46656
Answer:
(i) The prime factorisation of 216 is as follows:
| 2 | 216 |
| 2 | 108 |
| 2 | 54 |
| 3 | 27 |
| 3 | 9 |
| 3 | 3 |
| 1 |
∴ 216 = 2 ☓ 2 ☓ 2 ☓ 3 ☓ 3 ☓ 3 = 23 ☓ 33
Here, each prime factor appears as many times as a perfect multiple of 3, therefore, 216 is a
perfect cube.
(ii) The prime factorisation of 128 is as follows:
| 2 | 128 |
| 2 | 64 |
| 2 | 32 |
| 2 | 16 |
| 2 | 8 |
| 2 | 4 |
| 2 | 2 |
| 1 |
∴ 128 = 2 ☓ 2 ☓ 2 ☓ 2 ☓ 2 ☓ 2 ☓ 2
Here, each prime factor does not appear as many times as a perfect multiple of 3. Therefore, 128 is not a perfect cube.
(iii)The prime factorisation of 1000 is as follows.
| 2 | 1000 |
| 2 | 500 |
| 2 | 250 |
| 5 | 125 |
| 5 | 25 |
| 5 | 5 |
| 1 |
∴ 1000 = 2 ☓ 2 ☓ 2 ☓ 5 ☓ 5 ☓ 5 = 23 ☓ 53
Here, as each prime factor appears as many times as a perfect multiple of 3, therefore, 1000 is a perfect cube.
(iv)The prime factorisation of 100 is as follows.
| 2 | 100 |
| 2 | 50 |
| 5 | 25 |
| 5 | 5 |
| 1 |
∴ 100 = 2 ☓ 2 ☓ 5 ☓ 5
Here, each prime factor does not form triplet group(s). Therefore, 100 is not a perfect cube.
(iv) The prime factorisation of 46656 is as follows.
| 2 | 46656 |
| 2 | 23328 |
| 2 | 11664 |
| 2 | 5832 |
| 2 | 2916 |
| 2 | 1458 |
| 3 | 729 |
| 3 | 243 |
| 3 | 81 |
| 3 | 27 |
| 3 | 9 |
| 3 | 3 |
| 1 |
46656 = 2 ☓ 2 ☓ 2 ☓ 2 ☓ 2 ☓ 2 ☓ 3 ☓ 3 ☓ 3 ☓ 3 ☓ 3 ☓ 3
= 23 ☓ 23 ☓ 33 ☓ 33
Here, each prime factor appears as many times as a perfect multiple of 3,
∴ 46656 is a perfect cube.
Q2: Find the smallest number by which each of the following numbers must be multiplied to obtain a perfect cube.
Wednesday, 1 January 2014
CBSE Class 6 - History - CH 11 - New Empires and Kingdoms
New Empires and Kingdoms
![]() |
| Coin showing Samudraguta with Garuda pillar credits:wikimedia |
(Q & A)
Q1: Name the famous rulers of Gupta dynasty?
Answer: Samudragupta and Chandragupta II (Vikramaditya)
Q2: What do you mean by Prashasti?
Answer: Prashasti, a Sanskrit word, meaning ‘in praise of’. Generally, it is an inscription written in praise of rulers. It also tells about the genealogy of the rulers.
Q3: Who composed Prashasti of Samudragupta and where it is inscribed at?
Answer: Harishena composed a long poem in praise of King Samudragupta. It is inscribed on Ashokan pillar at Allahabad.
Q4: What was the old name of Allahabad?
Answer: Prayag
Q5: Who was the founder of Gupta dynasty?
Answer: Chandragupta I
Q6: Write a short note on Chandragupta I
Answer:
- Chandragupta I, the first ruler of Gupta dynasty, ascended throne of Magadha in 320 AD.
- He married to Kumaradevi, a princess of Lichchavi tribe.
- He expanded his kingdom upto Allahabad and took the title of Maharajadhiraj.
Saturday, 28 December 2013
CBSE Class 7 - Science - CH 14 - Electric Current and Its Effects (MCQs)
Electric Current and its Effects
(MCQs)
Q1: The unit to measure electric resistance is:
(a) Joule
(b) Ohm
(c) Ampere
(d) Volt
Q2: The device used to make or break an electric circuit is:
(a) Resistor
(b) Battery
(c) Switch
(d) Ammeter
Q3: When an electric current passes through a solenoid, it acts as a/an
(a) insulator
(b) electric bell
(c) resistor
(d) bar magnet
Q4: Which of the following is an essential element in an electric circuit?
(MCQs)
![]() |
| Why CFL is better than electric bulb? |
Q1: The unit to measure electric resistance is:
(a) Joule
(b) Ohm
(c) Ampere
(d) Volt
Q2: The device used to make or break an electric circuit is:
(a) Resistor
(b) Battery
(c) Switch
(d) Ammeter
Q3: When an electric current passes through a solenoid, it acts as a/an
(a) insulator
(b) electric bell
(c) resistor
(d) bar magnet
Q4: Which of the following is an essential element in an electric circuit?
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