Question:
A person writes a letter to four of his friends. He asks each one of them to copy the letter and mail to four different persons with instruction that they move the chain similarly. Assuming that the chain is not broken and that it costs 50 paise to mail one letter. Find the amount spent on the postage when 8th set of letter is mailed
Answer:
Gien in the question
1st person post 4 letters to his 4 friends.
Now these 4 persons post the letters to 4 friends each.
So total number of letter-post = 4*4 =16
Now this chain continues till 8th set.
Now series is 4, 4*4, 4*4*4,.........
4, 16, 46,................up to 8 terms.
This forms a GP where
first term a = 4
common ratio r = 16/4 = 4
number of terms n = 8
Now sum of GP = a(rn - 1)/(r - 1)
= 4*(48 - 1)/(4-1)
= 4*(65536 - 1)/3
= (4*65535)/3
Given cost of one letter = 0.50 rupee
Total cost = (4*65535*0.50)/3 = 4*21845*0.5043690 = 43690
So total amount spent on the postage when 8th set of letter is mailed = 43690 rupees
Not what you are looking for? Go ahead and submit the question, we will get back to you.
