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प्रश्न
A coin is tossed 5 times. Find the probability of getting (i) at least 4 heads, and (ii) at most 4 heads.
उत्तर
Total number of the probability of tossing a coin 5 times is 32
(i) Probability of getting at least 4 heads
P(X=4) + P(X=5)
`""^5C_4 (1/2)^1 (1/2)^4 + ""^5C_5 (1/2)^0 (1/5)^5`
= `""^5C_4 (1/2)^5 + ""^5C_5 (1/2)^5`
= `6/32 = 3/16`
(ii) Probability of getting at most 4 head
P(X=1) + P(X=2) + P(X=3) + P(X=4)
`""^5C_1 (1/2)^5 + ""^5C_2 (1/2)^5 + ""^5C_3 (1/2)^5 + ""^5C_4 (1/2)^5`
= `(1/2)^5` [5+ 10 + 10 + 5]
= `(15)/(16)`
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