'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 can 3 letters be posted in four letter boxes in a village ? If all the three letters are not posted in the same letter box. Find the corresponding number of ways of posting.

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 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.

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.

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.

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.

Statement -1 : Six different balls are put in three different boxes, no box being empty, the probability of putting balls in boxes in equal numbers is 1/6 Statement-2 : Six letters are posted in 3 letter boxes. The probability that no letter box remains empty is 20/27

Mohan post a letter to Sohan. It is known that one letter out of 10 letters do not reach its destination. If it is certain that Sohan will reply if he receives the letter. If A denotes the event that the Sohan receives the letter and B denotes the event that Mohan gets a reply, then