## Chapter 9 Class 11 Sequences and Series | Extra Questions

Q1. Insert five numbers between 8 and 26 such that the resulting sequence is an A.P.

Ans: 11, 14, 17, 20, 23.

Q2. Show that the sum of (m+n)^{th} and (m–n)^{th} terms of an A.P. is equal to twice the m^{th} term.

Q3. Find the sum of integers from 1 to 100 that are divisible by 2 or 5.

Ans: 3050

Q4. Is 309 a term of the AP 11, 17, 23….?

Ans: No

Q5. If the AM between the a^{th} and b^{th} terms of an AP be equal to the AM between the c^{th} and d^{th} term of it then prove that a + b = c + d

Q6. A carpenter was hired to build 192 window frames. The first day he made five frames and each day, thereafter he made two more frames than he made the day before. How many days did it take him to finish the job?

Ans: 12 days