A die is thrown a fixed number of times. If probability of getting even number 3 times is same as the probability of getting even number 4 times, then
A die is thrown a fixed number of times. If probability of getting even
number 3 times is same as the probability of getting even number 4 times,
then probability of getting even number exactly once is
`1//6`
b. `1//9`
c. `5//36`
d. `7//128`
A. `1//6`
B. `1//9
C. `5//36`
D. `7//128`
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Correct Answer - D
According to the givn condition,
`""^(n)C_(3)((1)/(2))^(n)=""^(n)C_(4)((1)/(2))^(n),`
where n is the number of times die is thrown.
`therefore""^(n)C_(3)=""^(n)C_(4)impliesn=7`
Thus, the required probability is
`=""^(7)C_(1)((1)/(2))^(7)=(7)/(2^(7))=(7)/(128)`
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