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Oliveboard Question of the day
Ishan being dyslexic, gets confused between the following pairs/sets of letters and writes them interchangeably: (B & D); (U, V & W); (E & F). He gets punished by his teacher whenever he makes three or more mistakes in a single word. Find the probability that he’ll get punished if he’s asked to write the word ‘OLIVEBOARD’. (Assume he makes no other mistake)
(d) None of these
Solution posted below. Click on the plus sign to view the solution.
Answer and Explanation
Answer key: a
As per the given conditions, he can possibly make mistake at four places
A – Letter V
B – Letter E
C – Letter B
D – Letter D
Let P(A), P(B), P(C) and P(D) denote the probabilities that he makes the above mistakes respectively.
P(A) = 2/3, P(B) = 1/2, P(C) = 1/2 and P(D) = 1/2.
Probability that he gets punished = P(A B C D) + P(A B C D) + P(A B C D) + P(A B C D) + P(A B C D)
= (2/3*1/2*1/2*1/2) + (2/3*1/2*1/2*1/2) + (2/3*1/2*1/2*1/2) + (1/3*1/2*1/2*1/2) + (2/3*1/2*1/2*1/2)