Two beads are drawn at random, one after the other, with replacement, from a box containing 5 red and 7 white identical beads. What is the probability that the beads are the same colour
A
\(\frac{119}{144}\)
B
\(\frac{95}{144}\)
C
\(\frac{37}{72}\)
D
\(\frac{49}{144}\)
E
\(\frac{1}{6}\)
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
To find the probability that two beads drawn (with replacement) are of the same color, we consider two cases: both red and both white.
Beads = 5, White beads = 7, Total beads = 12
Both Red:
\(P(\text{Red}) = \frac{5}{12}, \quad P(\text{Both Red}) = \frac{5}{12} \times \frac{5}{12} = \frac{25}{144}\)
Both White:
\(P(\text{White}) = \frac{7}{12}, \quad P(\text{Both White}) = \frac{7}{12} \times \frac{7}{12} = \frac{49}{144}\)
Total Probability of Same Color:
\(P(\text{Same Color}) = \frac{25}{144} + \frac{49}{144} = \frac{74}{144} = \frac{37}{72}\)
The probability that the two beads are the same color is \( \frac{37}{72}\).
Source: Myschool Past Questions Archive (Record #41861)