Subject
Quantitative Aptitude
Topic
Probability
In a box, 4 coins of ten rupees, 2 coins of five rupees, 2 coins of two rupees and 2 coins of one rupee are put. Now, three coins are taken out randomly. What is the probability that the amount drawn is 12 rupees?
In a box, 4 coins of ten rupees, 2 coins of five rupees, 2 coins of two rupees and 2 coins of one rupee are put. Now, three coins are taken out randomly. What is the probability that the amount drawn is 12 rupees?
ক)
1/5খ)
1/6গ)
3/16ঘ)
1/10ঙ)
1/20Explanation
There are 4 coins of ten rupees, 2 coins of five rupees, 2 coins of two rupees and 2 coins of one rupee. Total coins = 4 + 2 + 2 + 2 = 10 Total number of ways in which 3 coins can be taken out = 10 C 3 = 120 Amount drawn can be 12 rupees in the following cases: i) 1 coin of ten rupees and 2 coins of 1 rupee This can be done in 4 C 1 x 2 C 2 ways, i.e. 4 x 1 = 4 ways. ii) 2 coins of five rupees and 1 coin of 2 rupees This can be done in 2 C 2 x 2 C 1 ways, i.e. 1 x 2 = 2 ways. Total number of ways in which 10 rupees can be drawn = 4 + 2 = 6. ∴ Probability of drawing 10 rupees = (Total number of ways in which 10 rupees can be drawn in three coins/ Total number of ways in which 3 coins can be drawn) = 6/120 = 1/20.Related questions
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