A student has to take two quizzes tomorrow. He has only enough time to study for one of them.

- The history quiz has 4 true-or-false questions.
- The science quiz has 3 multiple-choice questions.

The student calculates the probability that he will get all the questions correct by guessing.

\begin{tabular}{|c|c|c|}
\hline
& To get 100\% correct: & [tex]$P$[/tex] (guess is correct) \\
\hline
History & \begin{tabular}{c}
Answer 4 of 4 \\
correctly.
\end{tabular} & 0.0625 \\
\hline
Science & \begin{tabular}{c}
Answer 3 of 3 \\
correctly.
\end{tabular} & 0.008 \\
\hline
\end{tabular}

The student will study for the quiz on which he is likely to do worse by guessing. Which quiz should he study for?



Answer :

Let's calculate the probability of the student getting all questions correct by guessing for each quiz.

### History Quiz
- The history quiz consists of 4 true-or-false questions.
- The probability of guessing a true-or-false question correctly is [tex]\( 0.5 \)[/tex].

To calculate the probability of getting all 4 questions correct:
[tex]\[ P_{history} = 0.5^4 \][/tex]

### Calculation for History Quiz:
[tex]\[ P_{history} = 0.5 \times 0.5 \times 0.5 \times 0.5 = 0.5^4 = 0.0625 \][/tex]

So, the probability of the student getting all the history questions correct by guessing is 0.0625.

### Science Quiz
- The science quiz consists of 3 multiple-choice questions.
- The probability of guessing a multiple-choice question correctly is [tex]\( 0.2 \)[/tex].

To calculate the probability of getting all 3 questions correct:
[tex]\[ P_{science} = 0.2^3 \][/tex]

### Calculation for Science Quiz:
[tex]\[ P_{science} = 0.2 \times 0.2 \times 0.2 = 0.2^3 = 0.008 \][/tex]

So, the probability of the student getting all the science questions correct by guessing is 0.008.

### Decision
The student is more likely to get worse on the quiz with the lower probability of getting all the questions correct by guessing.

- Probability of getting all history questions correct: [tex]\( 0.0625 \)[/tex]
- Probability of getting all science questions correct: [tex]\( 0.008 \)[/tex]

Since [tex]\( 0.008 \)[/tex] (science) is less than [tex]\( 0.0625 \)[/tex] (history), the student is more likely to do worse on the science quiz by guessing.

Therefore, the student should study for the Science quiz.