Three different coins are tossed together. Find the probability of getting:

$( i)$ exactly two heads
$( ii)$ at least two heads
$( iii)$ at least two tails.


Given: Three different coins are tossed together.

To do: To Find the probability of getting

$( i)$. exactly two heads

$( ii)$. at least two heads

$( iii)$. at least two tails.

Solution:

When three coins are tossed together, the possible outcomes are

$( HHH,\ HTH,\ HHT,\ THH,\ THT,\ TTH,\ HTT,\ TTT)$

$\therefore$ Total number of possible outcomes $=\ 8$

$( i)$. Favorable outcomes of exactly two heads are $( HTH,\ HHT,\ THH)$

$\therefore$ Total number of favourable outcomes $= 3$

$\therefore \ P( exactly\ two\ heads) =\frac{no.\ of\ favourble\ outcomes}{no.\ of\ total\ outcomes} =\frac{3}{8}$

$( ii)$. Favourable outcomes of at least two heads are $( HHH,\ HTH,\ HHT,\ THH)$

$\therefore$ Total number of favourable outcomes $=4$

$\therefore \ P( at\ least\ two\ heads) \ =\frac{no.\ of\ favourble\ outcomes}{no.\ of\ total\ outcomes}=\frac{4}{8}=\frac{1}{2}$

$( iii)$. Favourable outcomes of at least two tails are $( THT,\ TTH,\ HTT,\ TTT)$

$\therefore$ Total number of favourable outcomes$=4$

$\therefore \ P( at\ least\ two\ tails) =\frac{no.\ of\ favourble\ outcomes}{no.\ of\ total\ outcomes}=\frac{4}{8}=\frac{1}{2}$

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Updated on: 10-Oct-2022

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