High School

Specific rounding instructions: Round your answers to two decimal places. Show both decimal places (e.g., 5.06).

Shannon is traveling from New York City to Washington, D.C. She wants to go by train to enjoy 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.

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

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

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

c. Based on your first two answers, which train fare would have a percentile rank of approximately [tex]82\%[/tex]? [tex]\square[/tex]

Answer :

Sure, let's solve this problem step-by-step!

### Step-by-Step Solution:

#### a. Find the percentile rank for a fare of [tex]\( \$119 \)[/tex].

First, we list out all the fares:

[tex]\[
49, 88, 88, 88, 119, 133, 133, 133, 161, 171, 173, 173, 173, 272, 284,
49, 88, 88, 88, 119, 133, 133, 161, 161, 173, 173, 173, 173, 272, 284,
88, 88, 88, 119, 119, 133, 133, 161, 161, 173, 173, 173, 272, 272, 284,
88, 88, 88, 119, 133, 133, 133, 161, 171, 173, 173, 173, 272, 272, 284,
88, 88, 88, 119, 133, 133, 133, 161, 171, 173, 173, 173, 272, 284, 284,
88, 88, 88, 119, 133, 133, 133, 161, 171, 173, 173, 173, 272, 284, 284
\][/tex]

In total, there are 90 fares.

To calculate the percentile rank for a fare of [tex]\( \$119 \)[/tex]:
1. Count how many fares are less than [tex]\( 119 \)[/tex].
2. Count how many fares are equal to [tex]\( 119 \)[/tex].
3. Use the percentile rank formula.

Total number of fares below [tex]\( \$119 \)[/tex] is [tex]\( 12 \)[/tex].
Total number of fares equal to [tex]\( \$119 \)[/tex] is [tex]\( 6 \)[/tex].

The formula to find percentile rank is:
[tex]\[ \text{Percentile Rank} = \left( \frac{\text{Number of values below}}{\text{Total number of values}} \right) \times 100 + \left( \frac{\text{Number of values equal}}{\text{Total number of values}} \right) \times 50 \][/tex]

Let's plug in the values:

[tex]\[ \text{Percentile Rank} = \left( \frac{12}{90} \right) \times 100 + \left( \frac{6}{90} \right) \times 50 \][/tex]
[tex]\[ \text{Percentile Rank} = 13.33 + 3.33 \][/tex]
[tex]\[ \text{Percentile Rank} \approx 26 \][/tex]

The percentile rank for a fare of [tex]\( \$119 \)[/tex] is approximately 26%.

#### b. Find the percentile rank for a fare of [tex]\( \$272 \)[/tex].

To calculate the percentile rank for a fare of [tex]\( \$272 \)[/tex]:
1. Count how many fares are less than [tex]\( 272 \)[/tex].
2. Count how many fares are equal to [tex]\( 272 \)[/tex].
3. Use the percentile rank formula.

Total number of fares below [tex]\( \$272 \)[/tex] is [tex]\( 65 \)[/tex].
Total number of fares equal to [tex]\( \$272 \)[/tex] is [tex]\( 7 \)[/tex].

Let's plug in the values:

[tex]\[ \text{Percentile Rank} = \left( \frac{65}{90} \right) \times 100 + \left( \frac{7}{90} \right) \times 50 \][/tex]
[tex]\[ \text{Percentile Rank} = 72.22 + 3.89 \][/tex]
[tex]\[ \text{Percentile Rank} \approx 87 \][/tex]

The percentile rank for a fare of [tex]\( \$272 \)[/tex] is approximately 87%.

#### c. Based on your first two answers, which train fare would have a percentile rank of approximately [tex]\( 82\% \)[/tex] ?

To find the fare with a percentile rank of approximately 82%:
1. Sort the fares.
2. Find the position in the sorted list that corresponds to the 82nd percentile.

Since 90 fares exist, the index to look at is:
[tex]\[ \text{Index} = \left( \frac{82}{100} \times 90 \right) - 1 \][/tex]
[tex]\[ \text{Index} \approx 73 \][/tex]

So we look at the fare in the 74th position (since we start from 0). The fare at this position corresponds to [tex]\( \$173 \)[/tex].

The fare with a percentile rank of approximately [tex]\( 82\% \)[/tex] is [tex]\($173\)[/tex].

### Final Answers:
a. The percentile rank for a fare of [tex]\( \$119 \)[/tex] is [tex]\( 26\% \)[/tex].
b. The percentile rank for a fare of [tex]\( \$272 \)[/tex] is [tex]\( 87\% \)[/tex].
c. The fare with a percentile rank of approximately [tex]\( 82\% \)[/tex] is [tex]\( \$173 \)[/tex].