'A' writes a letter to his friend 'B' and gives it to his son to post it in a letter box, the reliability of his son being `3/4`. The probability that a letter posted will get delivered is `8/9` .At a later date, 'A' hears from 'B' that the letter has not reached him. Find the probability that the son did not post the letter at all .

A' writes a letter to his friend B and oes not receive a reply, it is known that one out of 'n' letters does not reach it's destination. What is the probability that 'B' didn't receive the letter ? It is certain that 'B' would have replied , if he received the letter.

In how many ways 3 letters can be posted in 4 letter-boxes,if all the letters are not posted in the same letter-box

A person write 4 letters and addresses 4 envelopes. If the letters are placed in the envelopes at random, then the probability that all letters are not placed in the right envelopes, is a. 1/4 b. 11/24 c. 15/24 d. 23/24

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 spend on the postage when 8th set of letter is mailed.

find the underline word given option The son writes meaningless letters to his father.

Dipesh writes letters to four of his friends. He asks each of them to copy the letter and mail to four different persons with the request that they continue the chain similarly. Assuming that the chain is not broken and that it costs 25 paise to mail one letter, find the total money spent on postage till the 8th set of letters is mailed.

A man 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 the instruction that they move the chain similarly. Assuming that the chain is not broken and it costs Rs. 4 to mail one letter, find the amount spent on postange when 6th set of letters is mailed.