Solutions – Homework 3
5.4 Fear of flying?
:
a) This would be considered a “long run” of trials. A long run refers to many, many
trials. 31 million flights certainly would qualify as many trials.
b) The probability of a fatal accident on a particular flight is 10/31,000,000 =
0.0000003.
5.8 Heart transplant
:
In the absence of pre-existing data, Dr. Barnard relied on the subjective definition of
probability. He used his own judgment rather than objective information such as data.
5.18 Two girls
:
a) The sample space includes FF, FM, MF, and MM.
b) One of these four possibilities is FF; thus the probability that the family has one girl is
1/4 = 0.25.
c) If the chance of a girl is 0.49, then the probability that the family will have two girls
is: P(A and B) = P(A) X P(B) = 0.49 X 0.49 = 0.24.
5.19 All girls in a family:
a)
The sample space for the possible genders of four children is FFFF, FFFM, FFMF,
FFMM, FMFF, FMFM, FMMF, FMMM, MMMM, MMMF, MMFM, MMFF,
MFMM, MFMF, MFFM, and MFFF.
b) There are 16 possible outcomes, only one of which is all girls. The probability of