# Class 11 Lecture 4 Sequences and Series

“Leaders Set High Standards. Refuse To Tolerate Mediocrity Or Poor Performance”

# Lecture - 4 Chapter 9 Sequences & Series

 NCERT EXERCISE 9.2

Question 13. If the sum of n terms of an A.P. is $$3n^2+5n$$ and its mth term is 164, find the value of m.

Question 14. Insert five numbers between 8 and 26 such that the resulting sequence is an A.P.

Question 15. If $$\frac{a^n+b^n}{a^{n-1}+b^{n-1}}$$ is the A.M. between a and b, then find the value of n.

Question 16. Between 1 and 31, m numbers have been inserted in such a way that the resulting sequence is an A. P. and the ratio of 7th and (m – 1)th numbers is 5 : 9. Find the value of m.

Question 17. A man starts repaying a loan as first installment of Rs. 100. If he increases the installment by Rs 5 every month, what amount he will pay in the 30th installment?

Question 18. The difference between any two consecutive interior angles of a polygon is 5°. If the smallest angle is 120° , find the number of the sides of the polygon.