Question

A multiple choice test has two parts. There are 4^12 ways to answer the 12 questions in Part A. There are 4^5 ways to answer the 5 questions on part B. How many ways are there to answer all 17 questions? If you guess each answer, what is the probability you will get them all right

Answer 1

Using the Fundamental Counting Theorem and the probability concept, it is found that:

• There are $4^{17}$ ways to answer all 17 questions.

• $4^{-17}$ probability you will get them all right.

What is the Fundamental Counting Theorem?

• It is a theorem that states that if there are n things, each with $n_1, n_2, \cdots, n_n$ ways to be done, each thing independent of the other, the number of ways they can be done is:

$N = n_1 \times n_2 \times \cdots \times n_n$

What is a probability?

• A probability is given by the number of desired outcomes divided by the number of total outcomes.

In this problem:

• The questions in part A and in part B are independent.

• For the 12 questions in part A, there are $4^{12}$ ways to answer, hence $n_1 = 4^{12}$.

• For the 5 questions in part B, there are $4^{5}$ ways to answer, hence $n_2 = 4^{5}$.

Then:

$N = n_1 \times n_2 = 4^{12} \times 4^5 = 4^{17}$

There are $4^{17}$ ways to answer all 17 questions.

Only one outcome in which all the guesses are correct, hence:

$p = \frac{1}{4^{17}} = 4^{-17}$ probability you will get them all right.

You can learn more about the Fundamental Counting Theorem at brainly.com/question/24314866