Question

In the sequence 1, 2, 2, 4, 4, 4, 4, 8, 8, 8, 8, 8, 8, 8, 8, . . . . . , where $$n$$ consecutive terms have the value $$n,$$ the $$1025^{th}$$  term is

A. $${2^9}$$
B. $${2^{10}}$$  
C. $${2^{11}}$$
D. $${2^8}$$
Answer :   $${2^{10}}$$
Solution :
Let the $$1025^{th}$$  term = $$2^n.$$ Then
$$\eqalign{ & 1 + 2 + 4 + 8 + ..... + {2^{n - 1}} < 1025 \leqslant 1 + 2 + 4 + 8 + ..... + {2^n} \cr & \therefore \,\,{2^n} - 1 < 1025 < {2^{n + 1}} - 1\,\,{\text{or, }}{2^n} < 1026 < {2^{n + 1}} \cr & \Rightarrow \,\,n = 10. \cr} $$

Releted MCQ Question on
Algebra >> Sequences and Series

Releted Question 1

If $$x, y$$ and $$z$$ are $${p^{{\text{th}}}},{q^{{\text{th}}}}\,{\text{and }}{r^{{\text{th}}}}$$   terms respectively of an A.P. and also of a G.P., then $${x^{y - z}}{y^{z - x}}{z^{x - y}}$$   is equal to:

A. $$xyz$$
B. 0
C. 1
D. None of these
Releted Question 2

The third term of a geometric progression is 4. The product of the first five terms is

A. $${4^3}$$
B. $${4^5}$$
C. $${4^4}$$
D. none of these
Releted Question 3

The rational number, which equals the number $$2.\overline {357} $$   with recurring decimal is

A. $$\frac{{2355}}{{1001}}$$
B. $$\frac{{2379}}{{997}}$$
C. $$\frac{{2355}}{{999}}$$
D. none of these
Releted Question 4

If $$a, b, c$$  are in G.P., then the equations $$a{x^2} + 2bx + c = 0$$     and $$d{x^2} + 2ex + f = 0$$     have a common root if $$\frac{d}{a},\frac{e}{b},\frac{f}{c}$$   are in-

A. A.P.
B. G.P.
C. H.P.
D. none of these

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