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A survey asked students whether they have any siblings and pets. The survey data are shown in the relative frequency table.

\begin{tabular}{|c|c|c|c|}
\hline & Siblings & No siblings & Total \\
\hline Pets & 0.3 & 0.15 & 0.45 \\
\hline No pets & 0.45 & 0.1 & 0.55 \\
\hline Total & 0.75 & 0.25 & 1.0 \\
\hline
\end{tabular}

Given that a student does not have a sibling, what is the likelihood that he or she has a pet?

A. [tex]$60\%$[/tex]

B. About [tex]$33\%$[/tex]

C. [tex]$75\%$[/tex]

D. [tex]$15\%$[/tex]


Sagot :

To solve this problem, we need to calculate the conditional probability that a student has a pet given that they do not have any siblings. This can be approached step by step as follows:

1. Identify the relevant probabilities from the table:
- The probability that a student has pets and no siblings is given by the relative frequency [tex]\( \text{P}(\text{Pets and No Siblings}) \)[/tex]. From the table, this value is [tex]\( 0.15 \)[/tex].
- The probability that a student has no siblings is given by the relative frequency [tex]\( \text{P}(\text{No Siblings}) \)[/tex]. From the table, this value is [tex]\( 0.25 \)[/tex].

2. Use the definition of conditional probability:
The conditional probability of having pets given that a student has no siblings is defined as:
[tex]\[ \text{P}(\text{Pets}|\text{No Siblings}) = \frac{\text{P}(\text{Pets and No Siblings})}{\text{P}(\text{No Siblings})} \][/tex]

3. Substitute the probabilities into the formula:
[tex]\[ \text{P}(\text{Pets}|\text{No Siblings}) = \frac{0.15}{0.25} \][/tex]

4. Calculate the conditional probability:
[tex]\[ \text{P}(\text{Pets}|\text{No Siblings}) = \frac{0.15}{0.25} = 0.6 \][/tex]

5. Convert the probability into a percentage:
[tex]\[ 0.6 \times 100 = 60\% \][/tex]

Therefore, the likelihood that a student who does not have any siblings has a pet is [tex]\( 60\% \)[/tex].

The correct answer is:
A. [tex]\( 60\% \)[/tex]