** Test Your Skills **

Twenty sheets of aluminum alloy were examined for surface flaws. The frequency of the number of sheets with a given number of flaws per sheet was as follows:

What is the probability of finding a sheet chosen at random which contains 3 or more surface flaws?

Number of flaws | Frequency |
---|---|

0 | 4 |

1 | 3 |

2 | 5 |

3 | 2 |

4 | 4 |

5 | 1 |

6 | 1 |

What is the probability of finding a sheet chosen at random which contains 3 or more surface flaws?