A word consists of 11 letters in which there are 7 consonants and 4 vowels. If 2 letters are chosen

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14.Probability

easy

A word consists of $11$ letters in which there are $7$ consonants and $4$ vowels. If $2$ letters are chosen at random, then the probability that all of them are consonants, is

A

$\frac{5}{{11}}$

B

$\frac{{21}}{{55}}$

C

$\frac{4}{{11}}$

D

None of these

Solution

(b) Required probability $ = \frac{{{}^7{C_2}}}{{{}^{11}{C_2}}} = \frac{{7\,\,.\,\,6}}{{11\,\,.\,\,10}} = \frac{{21}}{{55}}.$

Standard 11

Mathematics

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