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Use the data in the following table, which lists drive-thru order accuracy at popular fast food chains. Assume that orders are randomly selected from those included in the table.

[tex]\[
\begin{tabular}{|l|c|c|c|c|}
\hline & A & B & C & D \\
\hline Order Accurate & 337 & 273 & 248 & 146 \\
\hline Order Not Accurate & 39 & 51 & 34 & 11 \\
\hline
\end{tabular}
\][/tex]

If two orders are selected, find the probability that they are both accurate. Complete parts (a) and (b) below.

a. Assume that the selections are made with replacement. Are the events independent?

The probability is [tex]$\square$[/tex]. The events [tex]$\square$[/tex] independent.
(Do not round until the final answer. Round to four decimal places as needed.)

Sagot :

Sure! Let's solve the problem step by step using the data provided:

1. Determine the total number of orders for each restaurant:
- For restaurant A:
[tex]\[ \text{Total orders} = 337 (\text{Accurate}) + 39 (\text{Not Accurate}) = 376 \][/tex]
- For restaurant B:
[tex]\[ \text{Total orders} = 273 (\text{Accurate}) + 51 (\text{Not Accurate}) = 324 \][/tex]
- For restaurant C:
[tex]\[ \text{Total orders} = 248 (\text{Accurate}) + 34 (\text{Not Accurate}) = 282 \][/tex]
- For restaurant D:
[tex]\[ \text{Total orders} = 146 (\text{Accurate}) + 11 (\text{Not Accurate}) = 157 \][/tex]

2. Calculate the total number of accurate orders and the total number of orders overall:
- Total accurate orders:
[tex]\[ 337 (\text{A}) + 273 (\text{B}) + 248 (\text{C}) + 146 (\text{D}) = 1004 \][/tex]
- Total number of orders overall:
[tex]\[ 376 (\text{A}) + 324 (\text{B}) + 282 (\text{C}) + 157 (\text{D}) = 1139 \][/tex]

3. Calculate the probability of selecting an accurate order:
[tex]\[ P(\text{Accurate}) = \frac{\text{Total number of accurate orders}}{\text{Total number of orders}} = \frac{1004}{1139} \approx 0.8815 \][/tex]

4. If selections are made with replacement, the probability of both being accurate is calculated as follows:
[tex]\[ P(\text{Both Accurate}) = P(\text{Accurate}) \times P(\text{Accurate}) = 0.8815 \times 0.8815 \approx 0.7770 \][/tex]
(Rounded to four decimal places as needed)

5. Determine if the events are independent:
Since selections are made with replacement, the outcome of the first selection does not affect the outcome of the second selection. Therefore, the events are independent.

Combining all the results, we have:
- The probability that both orders are accurate is approximately [tex]\(0.7770\)[/tex].
- The events are independent.

Thus, the answer is:
The probability is [tex]\(0.7770\)[/tex]. The events are independent.