Chapter 12.7, Problem 4CYP

To determine

To find: the probability associated with the number of answer on the last 6 question.

Answer to Problem 4CYP

Sample. .

Explanation of Solution

Given:

Rickey guessed last 6 question of MCQ.

Each question has 4 option.

Calculation:

According to the question, total number of questions is 6.

Expand the binomial ${\left(s+f\right)}^n$ with $n=4$

There are 4 equal possibilities on last 6 question:

So, $s=\frac{1}{4}=0.25,f=1-0.25=0.75$

Now,

  $\begin{array}{l}{\left(s+f\right)}^n\\ ={\left(0.25\right)}^4+4{\left(0.25\right)}^3\left(0.75\right)+6{\left(0.25\right)}^2{\left(0.75\right)}^2+4\left(0.25\right){\left(0.75\right)}^3+{\left(0.75\right)}^4\\ =\text{4correct 3correct 2correct 1 correct 0correct }\\ =1\end{array}$