Page 62 - Mathematics Class - XI

Viva-Voce

1. What is meant by arithmetic progression?
Ans. An arithmetic progression (A.P.) is a sequence in which terms increase or decrease regularly by the same
constant. This constant is called common difference of the A.P.

2. Define arithmetic mean.
Ans. If a, A, b are in A.P., then A is called the arithmetic mean of the numbers a and b and is given by
ab+
A =
2
3. What is geometric progression?

Ans. A sequence is said to be a geometric progression or G.P., if the ratio of any term to its preceding term is
same throughout. This constant factor is called the common ratio.
4. What is geometric mean?

Ans. If a, G, b are in G.P., then G is known as geometric mean of the numbers a and b and is given by G = ab
5. What is the geometric mean of two positive numbers 2 and 8?

×
Ans. Geometric mean = ab = 28
= 16 = 4

MCQs

1. The value of (32) × (32) × (32) ................ ∞ will be
1/36
1/6
a) 64 b) 16 c) 32 d) 0
2. The two geometric mean terms between 1 and 64 will be
a) 1 and 64 b) 4 and 16 c) 2 and 16 d) 8 and 16

3. If for any A.P., S = 2n + 5n, then the value of its 10 term is
2
th
n
a) 10 b) 12 c) 0 d) None of these
4. log 2, log (2 – 1), log (2 + 3) are in A.P. then the value of x will be
x
x
a) 0 b) 1 c) 1 d) None of these
2
5. If the first, second and the last term of an A.P. are a, b and 2a then the sum of series is

ab ab 3ab
a) b) c) d) None of these

2 ba ba− 2 ba

6. The geometric mean between –9 and –4 is
a) 6 b) –6 c) 7 d) None of these
Answers: 1. a) 64 2. b) 4 and 16 3. d) None of these
3ab
4. d) None of these 5. c) 2 ba 6. a) 6

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