To do Check out Topic
Exercises 9–32 Example 19 Conditional probability
Exercises 33–52 Example 20 Determining whether
two events are
independent
Exercises 53–58 Example 22 Multiplication Rule
Exercises 59–66 Example 23 Multiplication Rule for
two independent events
Exercises 67–70 Example 24 Sampling with
replacement
Exercises 71–74 Example 25 Sampling without
replacement
Exercises 79–84 Example 26 Determining
independence using the
alternative method
Exercises 85–92 Example 27 Conditional probability
for mutually exclusive
events
Exercises 93–100 Example 28 Multiple rule for
independent events
Exercises 100–104 Example 29 Solving an “at least”
problem
Exercises 75–78 Example 30 Applying the 1%
Guideline
Exercises 105–108 Example 31 Bayes' Rule

Table 26 presents a sample of 10 threatened and endangered mammals, and their continents. The contingency table for this data is given in Table 27.

Table 5.60: TABLE 26 Endangered and threatened mammals
Species Continent Endangered or
threatened?
Desert Bandicoot Australia Endangered
Grizzly Bear North America Threatened
Chimpanzee Africa Endangered
African elephant Africa Threatened
Koala Australia Threatened
Mountain gazelle Africa Endangered
Canada Lynx North America Threatened
Ocelot North America Endangered
Bighorn sheep North America Endangered
White rhino Africa Endangered
Table 5.61: TABLE 27 Contingency table of threatened and endangered species
Africa Australia North
America		 Total
Threatened 1 1 2 4
Endangered 3 1 2 6
Total 4 2 4 10

A mammal is to be chosen at random. Define the following events:

  • A: Continent is Africa
  • B: Continent is Australia
  • C: Continent is North America
  • E: Mammal is endangered
  • T: Mammal is threatened

For Exercises 9–22, use Table 27 to find the indicated probabilities.

Question 5.234

21. Compare (E given A) and (T given A). Among the mammals from Africa, is the higher proportion endangered or threatened?

5.3.21

Endangered