In Exercises 21–28, use the same list of 24 sorted Old Faithful eruption duration times given for Exercises 17–20. Find the indicated percentile or quartile.

P 40

Answer:

Step 1 of 1

Assume that the elements in a data set are rank ordered from the smallest to the largest. The values that divide a rank-ordered set of elements into 100 equal parts are called percentiles.

1 |
110 |

2 |
120 |

3 |
178 |

4 |
213 |

5 |
234 |

6 |
234 |

7 |
235 |

8 |
237 |

9 |
240 |

10 |
243 |

11 |
245 |

12 |
245 |

13 |
250 |

14 |
250 |

15 |
251 |

16 |
252 |

17 |
254 |

18 |
255 |

19 |
255 |

20 |
259 |

21 |
260 |

22 |
266 |

23 |
269 |

24 |
273 |

To find the 90th percentile for these (ordered) scores, start by multiplying 90% times the total number of scores, which gives 40% ∗ 24 = 9.6.

Rounding up to the nearest whole number 10, we get 243.