'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 .

Dear Student,
Please find below the solution to the asked query:

Let P  be the probabilty that son posts the letter.P=34Hence, probabilty that he does not post letter is given by:P¯=1-34=14Let Q be the probabilty that letter is delivered.Q=89Hence probability that letter is not delivered is given by:Q¯=1-89=19NowTotal probabilty that letter is not delivered to B=Probabilty that son does not post letter OR Son posts letter ANDletter is not deliveredTotal Probability=P¯+P×Q¯=14+34×19=14+112=412=13Probability that son did not post the letter at all=P¯Total Probability =1413=34 Answer

Hope this information will clear your doubts about this topic.

If you have any doubts just ask here on the ask and answer forum and our experts will try to help you out as soon as possible.

  • 3
What are you looking for?