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14.Probability
easy
A bag contains tickets numbered from $1$ to $20$. Two tickets are drawn. The probability that both the numbers are prime, is
A
$\frac{{14}}{{95}}$
B
$\frac{7}{{95}}$
C
$\frac{1}{{95}}$
D
None of these
Solution
(a) There are $8$ prime numbers $2,\,\,3,\,\,5,\,\,7,\,\,11,\,\,13,\,\,17,\,\,19.$
Hence required probability $ = \frac{{{}^8{C_2}}}{{{}^{20}{C_2}}} = \frac{{8.7}}{{20\,.\,19}} = \frac{{14}}{{95}}$.
Standard 11
Mathematics
