A bag contains 4 red, 2 green and 7 blue balls. What is the probability of drawing a red ball and the first ball drawn is blue? The balls drawn are replaced in the bag.

Category: QuestionsA bag contains 4 red, 2 green and 7 blue balls. What is the probability of drawing a red ball and the first ball drawn is blue? The balls drawn are replaced in the bag.
Editor">Editor Staff asked 11 months ago

A bag contains 4 red, 2 green and 7 blue balls. What is the probability of drawing a red ball and the first ball drawn is blue? The balls drawn are replaced in the bag.
 
(a) \(\frac {28}{169}\)
 
(b) \(\frac {8}{11}\)
 
(c) \(\frac {4}{128}\)
 
(d) \(\frac {14}{11}\)
 
The question was asked in final exam.
 
The question is from Probability topic in section Probability of Mathematics – Class 12
NCERT Solutions for Subject Clas 12 Math Select the correct answer from above options 
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1 Answers
Editor">Editor Staff answered 11 months ago

Right option is (a) \frac {28}{169}
 
Easiest explanation: Total number of balls = 4 + 2 + 7 = 13
 
The probability of the first ball to be blue = \frac {7}{13}
 
The probability of drawing red ball as the second ball = \frac {4}{13}
 
Total probability = \frac {7}{13} \times \frac {4}{13} = \frac {28}{169}