Chapter 12.3, Problem 30HP

To determine

To calculate: the probability that Aisha will be late at least 3 of the next 5 Wednesdays

Answer to Problem 30HP

The correct option is D

Explanation of Solution

Given information:

Aisha is late to practice $30$ % of the time each Wednesday because of French club.

Calculation:

All three sides of equilateral triangle are equal. Let a shows the side of the triangle. Then the altitude of the triangle is

  $h=\frac{\sqrt{3}}{2}a$

And perimeter of triangle is

  $P=3a$

Since perimeter is 45 so side will be,

  $\begin{array}{r}\hfill 45=3a\\ \hfill a=15\end{array}$

Therefore altitude is,

  $\begin{array}{l}h=\frac{\sqrt{3}}{2}a\\ =\frac{\sqrt{3}}{2}\cdot 15\\ =7.5\sqrt{3}\end{array}$

Hence, correct option is D