Binomial Theorem And Its Simple Applications Question 62

Question: For a positive integer n, Let $ a(n)=1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+…+\frac{1}{(2^{n})-1}. $ Then

Options:

A) $ a(100)\le 100 $

B) $ a(100)>100 $

C) $ a(200)\le 100 $

D) $ a(200)<100 $

Show Answer

Answer:

Correct Answer: A

Solution:

  • [a] It can be proved with the help of mathematical induction that $ \frac{n}{2}>a(n)\le n. $

$ \therefore \frac{200}{2}<a(200) $

$ \Rightarrow a(200)>100 $ and $ a(100)\le 100. $