A pair of dice is thrown 5 times. If getting a total of 7 is considered a success, then the probability of at least 3 success is : |
$46\left(\frac{1}{6}\right)^4$ $96\left(\frac{1}{6}\right)^4$ $625\left(\frac{1}{6}\right)^4$ $1250\left(\frac{1}{6}\right)^4$ |
$46\left(\frac{1}{6}\right)^4$ |
The correct answer is Option (1) → $46\left(\frac{1}{6}\right)^4$ Total thrown = 5 P(7 comes) = $\frac{1}{6}$ P(7 doesn't comes) = $\frac{5}{6}$ $={^5C}_3\frac{1}{63}×\frac{52}{62}+{^5C}_4\frac{1}{6}×\frac{5}{6}+{^5C}_5×\frac{1}{65}$ $=\frac{1}{64}\left(\frac{5×5×5×4}{2×6}+\frac{5×5}{6}+\frac{1}{6}\right)$ $=\frac{46}{64}$ |