Chapter 1.9, Problem 2PSA

To determine

To find the probability of the angle to be right when one of the five angles is selected at random.

Answer to Problem 2PSA

  $TheProbabilityis\frac{1}{5}$

Explanation of Solution

Given information: The angles can be classified as follows:

  $\begin{array}{l}Acuteangles:40°,50°and60°.\hfill \\ Rightangles:90°.\hfill \\ Obtuseangles:130°. \hfill \end{array}$

Formula used:

Probability means possibility.

The probability formula is defined as the possibility of an event to happen is equal to the ratio of the number of favorable outcomes and the total number of outcomes.

Probability of event to happen is

  $P\left(E\right)=Numberoffavourableoutcomes/TotalNumberofoutcomes$

Calculation:

In geometry and trigonometry, a right angle is an angle of exactly 90 degrees, corresponding to a quarter turn.

  

  

In our example, there is one favorable outcome, i.e. $90°$

There are five total number of outcomes, i.e. $40°,50°,60°,90°and130°$

Therefore, the probability will be

  $P\left(Angleisrightangle\right)=\frac{1}{5}=0.2=20\%.$