Probability of getting either all heads or all tails for exactly second time in 3^{rd} trial, if in

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14.Probability

normal

The probability of getting either all heads or all tails for exactly the second time in the $3^{rd}$ trial, if in each trial three coins are tossed, is

A

$\frac{3}{{16}}$

B

$\frac{3}{{32}}$

C

$\frac{3}{{64}}$

D

$\frac{3}{8}$

Solution

$P$ ( all tails or all heads in one trial) $ = \frac{1}{4}$

$\therefore $ $P$ (this happens second time in ${3^{rd}}$ trial)

$ = {\,^2}{C_1} \times \frac{1}{4} \times \frac{3}{4} \times \frac{1}{4} = \frac{3}{{32}}$

Standard 11

Mathematics

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