High School

Shannon is traveling from New York City to Washington, D.C., and she wants to go by train to see the views. Since she will be driving home with a family member, she only priced the cost of a one-way ticket on Amtrak for any time of day on February 15. Below is an ordered listing of all fares that were available for selection on that day.

[tex]\[
\begin{tabular}{lllllllllllllll}
49 & 88 & 88 & 88 & 119 & 133 & 133 & 133 & 161 & 171 & 173 & 173 & 173 & 272 & 284 \\
49 & 88 & 88 & 88 & 119 & 133 & 133 & 161 & 161 & 173 & 173 & 173 & 173 & 272 & 284 \\
88 & 88 & 88 & 119 & 119 & 133 & 133 & 161 & 161 & 173 & 173 & 173 & 272 & 272 & 284 \\
88 & 88 & 88 & 119 & 133 & 133 & 133 & 161 & 171 & 173 & 173 & 173 & 272 & 272 & 284 \\
88 & 88 & 88 & 119 & 133 & 133 & 133 & 161 & 171 & 173 & 173 & 173 & 272 & 284 & 284 \\
88 & 88 & 88 & 119 & 133 & 133 & 133 & 161 & 171 & 173 & 173 & 173 & 272 & 284 & 284
\end{tabular}
\][/tex]

a. Find the percentile rank for a fare of [tex]$\$119$[/tex]. Interpret your results.

b. Find the percentile rank for a fare of [tex]$\$272$[/tex]. Interpret your results.

c. Based on your answers to parts a and b of this problem, which train fare would have a percentile rank of approximately 82%?

Answer :

Sure! Let's go through the details to solve the problems given.

### a. Find the percentile rank for a fare of \[tex]$119. Interpret your results.

To find the percentile rank for a fare of \$[/tex]119, we need to determine what percentage of fares are less than or equal to \[tex]$119.

Step-by-Step Solution:
1. List all the fares given and count how many individual fares are present.
2. Count how many fares are less than or equal to \$[/tex]119.
3. Divide the number of fares less than or equal to \[tex]$119 by the total number of fares, then multiply by 100 to get the percentile.

From the provided data, let's list the fares as:
\[ 49, 88, 88, 88, 119, 133, 133, 133, 161, 171, 173, 173, 173, 272, 284, \]
\[ 49, 88, 88, 88, 119, 133, 133, 161, 161, 173, 173, 173, 173, 272, 284, \]
\[ 88, 88, 88, 119, 119, 133, 133, 161, 161, 173, 173, 173, 272, 272, 284, \]
\[ 88, 88, 88, 119, 133, 133, 133, 161, 171, 173, 173, 173, 272, 272, 284, \]
\[ 88, 88, 88, 119, 133, 133, 133, 161, 171, 173, 173, 173, 272, 284, 284, \]
\[ 88, 88, 88, 119, 133, 133, 133, 161, 171, 173, 173, 173, 272, 284, 284 \]

In total, there are \( 6 \times 15 = 90 \) fares.

Count the number of fares that are \$[/tex]119 or less:
- We see 11 fares of [tex]$88 and 1 fare of $[/tex]49 in each list.
- We also see 1 instance of [tex]$119 in each list.

Total number across all lists = \( 6 \times 3 (fares \leq 119) = 18 \).

Now calculate the percentile rank for \$[/tex]119:
[tex]\[ \text{Percentile Rank} = \left(\frac{18}{90}\right) \times 100 = 20\% \][/tex]

So, the percentile rank for the fare \[tex]$119 is 20%. This means 30% of the fares are less than or equal to \$[/tex]119.

### b. Find the percentile rank for a fare of \[tex]$272. Interpret your results.

Step-by-Step Solution:
1. Count how many fares are less than or equal to \$[/tex]272.
2. Use the same method as in part (a) to calculate the percentile.

In the fares given:
- We need to count all fares that are less than or equal to \[tex]$272.
- We see that \$[/tex]272 appears 12 times across the lists.

Total cumulative by this fare tier is:
[tex]\( \text{Cumulative tally:} = \number of fares < \$272 + 12
\[

Count the fares less than or equal to \$272:
- \( \text{Fares < 272:} = 82

So in total, \( 82 + 12 = 92 \)[/tex].

[tex]\[ \text{Percentile Rank} = \left(\frac{92}{90}\right) \times 100 = 91.11\%
\][/tex]

So, the percentile rank for the fare \[tex]$272 is 91.11%. This means 91.11% of the fares are less than or equal to \$[/tex]272.

### c. Which train fare would have a percentile rank of approximately 82%?

To find the train fare corresponding to the 82nd percentile:
1. Sort the fares in ascending order.
2. Identify the fare that corresponds to the 82nd percentile.

From the ordered combined list:
In total number of fares = 90.

Position number in the sorted list for 82nd percentile is:
[tex]\[ 82 \% \times 90 = 73.8
\][/tex]

Approximately [tex]\(74th\)[/tex] position corrects to 173 fare tier. So, any of the 173 from the ascending position count,

Therefore, the train fare corresponding to the 82nd percentile is $173.

Hope this solution helps clarify the concept of percentile ranks! Let me know if you have any further questions.