Three letters, to each of which corresponds an envelope, are placed in the envelopes at random. The probability that all the letters are not placed in the right envelopes, is

Engineering

Mathematics

Conditional Probability

Question

$\frac{1}{6}$

$\frac{5}{6}$

$\frac{1}{3}$

$\frac{2}{3}$

LiveFree JEE Main Previous Year Online Papers Live Free JEE Advance Previous Year Online Papers

College PredictorLive

Know your College Admission Chances Based on your Rank/Percentile, Category and Home State.

Get your JEE Main Personalised Report with Top Predicted Colleges in JoSA

Three letters can be placed in 3 envelopes in 3! ways, whereas there is only one way of placing them in their right envelopes.
So, probability that all the letters are placed in the right envelopes $= \frac{1}{3!}$
Hence, required probability $= 1 - \frac{1}{3!} = \frac{5}{6}$

Please subscribe our Youtube channel to unlock this solution.