An unbiased coin is tossed 3 times. If the third toss gets head, then the probability of getting at least…
An unbiased coin is tossed 3 times. If the third toss gets head, then the probability of getting at least one more head is
$3 / 4$
$1 / 4$
$1 / 2$
$1 / 3$
Solution
If the third toss gets head, then the outcomes are $\{\mathrm{HHH}, \mathrm{HTH}, \mathrm{THH}, \mathrm{TTH}\}$.
$P($ at least one head in first 2 trial $)=3 / 4$