SOLUTION: After tossing some coins, it is observed that the probability of obtaining 10 heads
and 15 tails is the same as the probability of obtaining 15 heads and 10 tails. Find
the least
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and 15 tails is the same as the probability of obtaining 15 heads and 10 tails. Find
the least
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Question 549504: After tossing some coins, it is observed that the probability of obtaining 10 heads
and 15 tails is the same as the probability of obtaining 15 heads and 10 tails. Find
the least number of coins tossed Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! After tossing some coins, it is observed that the probability of obtaining 10 heads and 15 tails
is the same as the probability of obtaining 15 heads and 10 tails.
Find the least number of coins tossed
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P(10 h and 15 t) = nC10(1/2)^n
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P(15 h and 10 t) = nC15(1/2)^n
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nC10 = nC15
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n!/(n-15)!*15! = n!/(n-10)!*10!
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(n-15)!*15! = (n-10)!*10!
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(n-15)!*15*14*13*12*11 = (n-10)!
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15*14*13*12*11 = (n-10)(n-11)(n-12)(n-13)(n-14)
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So n-10 = 15
n = 25
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Cheers,
Stan H.
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