Questions: 12. Shopping spree The figure is a cumulative relative frequency graph of the amount spent by 50 consecutive grocery shoppers at a store.
a. Estimate the interquartile range (IQR) of this distribution. Show your method.
b. One shopper spent 19.50. Estimate this person's percentile.
c. Explain why the graph is steepest between 10 and 30.
Transcript text: E-book-STATISTICS\&PROBABI
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12. Shopping spree The figure is a cumulative relative frequency graph of the amount spent by 50 consecutive grocery shoppers at a store.
Starnes \& Tabor, The Practice of Statistics, 6 e ,
o 2018 Bedford, Freeman \& Worth High
School Publishers
a. Estimate the interquartile range (IQR) of this distribution. Show your method.
b. One shopper spent $\$ 19.50$. Estimate this person's percentile.
c. Explain why the graph is steepest between $\$ 10$ and $\$ 30$.
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Oct 14
11:51 $\nabla$
Solution
Solution Steps
Step 1: Identify the Quartiles for IQR Calculation
To estimate the interquartile range (IQR), we need to find the first quartile (Q1) and the third quartile (Q3) from the cumulative relative frequency graph. Q1 is the 25th percentile, and Q3 is the 75th percentile.
Step 2: Determine Q1 and Q3 from the Graph
From the graph:
Q1 (25th percentile) corresponds to an amount spent of approximately $15.
Q3 (75th percentile) corresponds to an amount spent of approximately $35.
Step 3: Calculate the IQR
The IQR is calculated as the difference between Q3 and Q1.
\[ \text{IQR} = Q3 - Q1 = 35 - 15 = 20 \]
Final Answer
The estimated interquartile range (IQR) of the distribution is $20.