An unbiased coin is tossed seven times in a row, what is the probability of getting at least one head if on the first toss came the tail?
Correct Answer : a ) \(63 \over 64\)Explanation :
If on the first toss, the tail came, then there will be only 6 tosses remaining.
As the coin is unbiased, so there is a fair chance of getting a head and tail.
So, the total possible outcomes will be = 26 = 64
Thus, the number of outcomes on which no head came will be = 1
As we know that
Probability of getting no head if on the first toss tail came =\(1 \over 64\)
Therefore, probability of getting at least one head if on the first toss tail came = (1 – Probability of getting no head if on the first toss tail came)
Hence, (A) is the correct answer.
Such type of question is asked in various government exams like SSC CGL, SSC MTS, SSC CPO, SSC CHSL, RRB JE, RRB NTPC, RRB GROUP D, RRB OFFICER SCALE-I, IBPS PO, IBPS SO, RRB Office Assistant, IBPS Clerk, RBI Assistant, IBPS RRB OFFICER SCALE 2&3, etc. Try and attempt free mock tests at PendulumEdu.
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