14.Probability
easy

दो गेंद एक बॉक्स से बिना प्रतिस्थापित किए निकाली जाती है। बॉक्स में $10$ काली और $8$ लाल गेदें हैं तो प्रायिकता ज्ञात कीजिए प्रथम काली एवं दूसरी लाल हो।

A

$\frac{20}{81}$

B

$\frac{20}{81}$

C

$\frac{20}{81}$

D

$\frac{20}{81}$

Solution

Total number of balls $=18$

Number of red balls $=8$

Number of black balls $=10$

Probability of getting first ball black $=\frac{10}{18}=\frac{5}{9}$

The ball is replaced after the first draw.

Probability of getting second ball as red $=\frac{8}{18}=\frac{4}{9}$

Therefore, probability of getting first ball as black and second ball as red $=\frac{5}{9} \times \frac{4}{9}=\frac{20}{81}$

Standard 11
Mathematics

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