Aptitude Discussion

Q. |
A bag contains 7 green and 5 black balls. Three balls are drawn one after the other. The probability of all three balls being green, if the balls drawn are not replaced will be: |

✖ A. |
343/1728 |

✖ B. |
21/36 |

✖ C. |
12/35 |

✔ D. |
7/44 |

**Solution:**

Option(**D**) is correct

Here, $n(E)$\(=^7C_1\times ^5C_1\times ^5C_1\)

And, $n(S)$\(=^{12}C_1\times ^{11}C_1\times ^{10}C_1\)

\(P(S)=\dfrac{7\times6\times5}{12\times11\times 10 }\)

\(=\dfrac{7}{44}\)

**P V Gopalakrishnan**

*()
*

It should be 7c1X6c1x5c1