# NCERT Class 11-Math՚s: Chapter – 9 Sequence and Series Part 13 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 18**:

The third term of G. P. is . The product of its first terms is

(A)

(B)

(C)

(D) None of these

**Answer: (C)**

**Question 19**:

If 9 times the 9^{th} term of an A. P. is equal to times the 13^{th} term, then the term of the A. P. is

(A)

(B)

(C)

(D)

**Answer: (A)**

**Question 20**:

If *x*, 2*y*, 3*z* are in A. P. , where the distinct numbers *x*, *y*, *z* are in G. P. then the

common ratio of the G. P. is

(A) 3

(B)

(C)

(D)

**Answer: (B)**

**Question 21**:

If in an A. P. , and , where S*r* denotes the sum of *r* terms of the A. P. , then equals

(A)

(B)

(C)

(D)

**Answer: (C)**

**Question 22**:

Let denote the sum of the first terms of an A. P. If then is equal to

(A)

(B)

(C)

(D)

**Answer: (B)**

**Question 23**:

The minimum value of , is

(A) 2

(B) 4

(C) 1

(D) 0

**Answer: (B)**

**Question 24**:

Let denote the sum of the cubes of the first natural numbers and denote the sum of the first natural numbers. Then equals

(A)

(B)

(C)

(D) None of these

**Answer: (A)**

**Question 25**:

If denotes the nth term of the series then is

(A)

(B)

(C)

(D)

**Answer: (D)**

**Question 26**:

The lengths of three unequal edges of a rectangular solid block are in G. P. The volume of the block is and the total surface area is . The length of the longest edge is

(A)

(B)

(C)

(D)

**Answer: (A)**