Westonci.ca is your go-to source for answers, with a community ready to provide accurate and timely information. Experience the convenience of finding accurate answers to your questions from knowledgeable professionals on our platform. Explore comprehensive solutions to your questions from a wide range of professionals on our user-friendly platform.

Data compiled by the Highway Patrol Department regarding the use of seat-belts by drivers in a certain area after the passage of a compulsory seat-belt law:

[tex]\[
\begin{tabular}{|c|c|c|}
\hline
\textbf{Drivers} & \textbf{Percentage of Drivers in Group} & \textbf{Percent of Group Stopped for Moving Violation} \\
\hline
\text{Group I (using seat-belts)} & 61 & 0.4 \\
\hline
\text{Group II (not using seat-belts)} & 39 & 0.3 \\
\hline
\end{tabular}
\][/tex]

(a) If a driver in that area is stopped for a moving violation, what is the probability that he or she will have a seat-belt on? [tex]\(\square\)[/tex]

(b) If a driver in that area is stopped for a moving violation, what is the probability that he or she will not have a seat-belt on? [tex]\(\square\)[/tex]

Sagot :

Let's solve this step-by-step.

### Given Data:

We are provided with percentages regarding the use of seat-belts and the percentage of drivers stopped for moving violations in two groups:

- Group I (using seat-belts):
- Percentage of drivers in this group: [tex]\( 61\% \)[/tex]
- Percentage of drivers in this group stopped for a moving violation: [tex]\( 0.4\% \)[/tex]

- Group II (not using seat-belts):
- Percentage of drivers in this group: [tex]\( 39\% \)[/tex]
- Percentage of drivers in this group stopped for a moving violation: [tex]\( 0.3\% \)[/tex]

### Step-by-Step Solution:

#### Part (a): Probability that a stopped driver will have a seat-belt on.

1. Convert percentages to decimals:
- [tex]\( P(\text{Seat-belt on}) = 0.61 \)[/tex]
- [tex]\( P(\text{No seat-belt}) = 0.39 \)[/tex]
- [tex]\( P(\text{Stopped with seat-belt}) = 0.004 \)[/tex]
- [tex]\( P(\text{Stopped without seat-belt}) = 0.003 \)[/tex]

2. Calculate the total probability of being stopped:
[tex]\[ P(\text{Stopped}) = P(\text{Seat-belt on}) \times P(\text{Stopped with seat-belt}) + P(\text{No seat-belt}) \times P(\text{Stopped without seat-belt}) \][/tex]
[tex]\[ P(\text{Stopped}) = 0.61 \times 0.004 + 0.39 \times 0.003 = 0.00244 + 0.00117 = 0.00361 \][/tex]

3. Calculate the probability of having a seat-belt on when stopped:
[tex]\[ P(\text{Seat-belt on} \mid \text{Stopped}) = \frac{P(\text{Seat-belt on}) \times P(\text{Stopped with seat-belt})}{P(\text{Stopped})} \][/tex]
[tex]\[ P(\text{Seat-belt on} \mid \text{Stopped}) = \frac{0.61 \times 0.004}{0.00361} = \frac{0.00244}{0.00361} \approx 0.676 \][/tex]

Therefore, the probability that a stopped driver will have a seat-belt on is approximately [tex]\( 0.676 \)[/tex].

#### Part (b): Probability that a stopped driver will not have a seat-belt on.

1. Calculate the probability of not having a seat-belt on when stopped:
[tex]\[ P(\text{No seat-belt} \mid \text{Stopped}) = \frac{P(\text{No seat-belt}) \times P(\text{Stopped without seat-belt})}{P(\text{Stopped})} \][/tex]
[tex]\[ P(\text{No seat-belt} \mid \text{Stopped}) = \frac{0.39 \times 0.003}{0.00361} = \frac{0.00117}{0.00361} \approx 0.324 \][/tex]

Therefore, the probability that a stopped driver will not have a seat-belt on is approximately [tex]\( 0.324 \)[/tex].

### Summary:
- (a) The probability that a stopped driver will have a seat-belt on is approximately [tex]\( 0.676 \)[/tex].
- (b) The probability that a stopped driver will not have a seat-belt on is approximately [tex]\( 0.324 \)[/tex].