Chapter 10.2, Problem 21E

(a)

To determine

To calculate:

The probability value of the selection of endangered species is a bird

Answer to Problem 21E

The probability value of the selection of endangered species is a bird is $0.171$ .

Explanation of Solution

Given information:

	Endangered	Threatened
Mammals	$70$	$16$
Birds	$80$	$16$
Others	$318$	$142$

Calculation:

In the given problem, the number of species in the United States is categorized as endangered and threatened. That means here the selection of animals from the group and names the type of animal.

Consider,

Number of mammals: $m_e=70$

Number of birds: $b_e=70=80$

Number of other animals: $o_e=70=318$

Here, total numbers of mammals is calculated as:

  $\begin{array}{l}n=m_e+b_e+o_e\\ n=70+80+318\\ n=468\end{array}$

In the first draw need to select the endangered species as bird animal. Probability value of events $A$ of selection of bird from endangered species is calculated as:

  $\begin{array}{l}P\left(A\right)=\frac{b_e}{n}\\ P\left(A\right)=\frac{80}{468}\\ P\left(A\right)=0.171\end{array}$

(b)

To determine

To calculate:

The probability value of the selection of endangered species is a mammals

Answer to Problem 21E

The probability value of the selection of endangered species is a mammals is $0.814$ .

Explanation of Solution

Given information:

	Endangered	Threatened
Mammals	$70$	$16$
Birds	$80$	$16$
Others	$318$	$142$

Calculation:

In the given problem, the number of species in the United States is categorized as endangered and threatened. That means here the selection of animals from the group and names the type of animal.

Consider,

Number of mammals endangered: $m_e=70$

Number of mammals threatened: $m_t=16$

Here, total numbers of mammals is calculated as:

  $\begin{array}{l}n=m_e+m_t\\ n=70+16\\ n=86\end{array}$

In this draw need randomly selection of the mammals and results as selecting an endangered mamma. Probability value of events $B$ of selection of mammals as endangered is calculated as:

  $\begin{array}{l}P\left(B\right)=\frac{m_e}{n}\\ P\left(B\right)=\frac{70}{86}\\ P\left(B\right)=0.814\end{array}$