Q82 / 160 · TS EAMCET 2007 · Mathematics

A bag contains 6 white and 4 black balls. Two balls are drawn at random. The probability that they are of the same colour, is

  • A
    $1 / 15$
  • B
    $2 / 5$
  • C
    $4 / 15$
  • Correct answer
    D
    $7 / 15$

Solution

The number of ways to select 2 balls out of 10 $={ }^{10} C_2$ Number of ways to select 2 balls both white $={ }^6 C_2$. Number of ways to select 2 balls both black $={ }^4 C_2$ $\therefore$ The required probability $=\frac{{ }^6 C_2+{ }^4 C_2}{{ }^{10} C_2}=\frac{7}{15}$

Hence, the correct answer is option: 'D'.

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