Statistics Demystified, 2nd edition |

Stan Gibilisco |

Explanations for Quiz Answers in Chapter 3 |

1. If we compare two results (called outcomes) in an experiment and the probability
of one outcome has no effect on the probability of the other outcome, then we
define the two outcomes as independent. The correct choice is B. |

2. By definition, a single element of a sample space constitutes an outcome. In a single experiment, or in the course of multiple identical experiments, the sample space is the set of all possible outcomes. The correct choice is B. |

3. If we know the number
u,
If |

4. In Fig. 3-13 on page 104, the shaded rectangle has 1/10 the area
of the large rectangle (whose two bottom vertices bear the labels
x_{min} and x_{max}). Therefore,
the probability of any particular outcome falling between x
= a and x = b is 1/10, or 10%. We should
call this probability figure"approximate" because the
drawing doesn't indicate precise numerical values. The correct
choice is B. |

5. In a uniform distribution, the function holds
constant for all values of the random variable between a
specified minimum and a specified maximum. In Fig. 3-13, this fact shows
up in the form of a "flat top" (horizontal line) from the minimum value
point x_{min} to the maximum value point x_{max}.
The probability that an outcome will fall between x = a
and x = b equals the ratio of the area of the shaded
region to the area of the large rectangle. That's the same as the ratio of
the quantity b - a to the quantity x_{max} -
x_{min}. The correct choice is C. |

6. A mathematical probability figure, expressed as a ratio or
proportion, always lies between 0 and 1 inclusive. For a particular
outcome 0 ≤ where |

7. Statisticians determine mathematical probability figures on the basis of pure theory (that is, entirely on the results of hypotheses, logic, and calculations). The correct choice is A. |

8. Let's use the formula that tells us how to calculate the number
of permutations q
items taken r at a time. That formula, which appears on page 92, is
q! / (q - r)!In this case, we have six objects taken five at a time, so
= 6! / 1! = 6! = 1 x 2 x 3 x 4 x 5 x 6 = 720 The answer is C. |

9. To determine the number of combinations q items taken r at a time, we divide the number of
permutations by _{q}P_{r}r!. The formula, which we can find
on page 92, is
/ _{q}P_{r}r!When we derived the answer to Question 8, we calculated
The answer is A. |

10. As defined on page 71, an event is a
single test or trial in an experiment, or in the course of multiple
identical experiments. The correct choice is A. |