\( \frac{13}{66} \)
Total balls = \( 3 + 4 + 5 = 12 \). Total ways to draw 2 balls = \( \binom{12}{2} = 66 \).
Same color:
- Red: \( \binom{3}{2} = 3 \)
- White: \( \binom{4}{2} = 6 \)
- Blue: \( \binom{5}{2} = 10 \)
Total favorable = \( 3 + 6 + 10 = 19 \).
Probability = \( \frac{19}{66} \).
Thus, the answer is \( \frac{19}{66} \).
Three distinct numbers are selected randomly from the set \( \{1, 2, 3, \dots, 40\} \). If the probability, that the selected numbers are in an increasing G.P. is \( \frac{m}{n} \), where \( \gcd(m, n) = 1 \), then \( m + n \) is equal to:
A board has 16 squares as shown in the figure. Out of these 16 squares, two squares are chosen at random. The probability that they have no side in common is: