Answer:
The IQR is given by:

If we want to find any possible outliers we can use the following formulas for the limits:


And if we find the lower limt we got:


So then the left boundary for this case would be 3 days
Step-by-step explanation:
For this case we have the following 5 number summary from the data of 144 values:
Minimum: 9 days
Q1: 18 days
Median: 21 days
Q3: 28 days
Maximum: 56 days
The IQR is given by:

If we want to find any possible outliers we can use the following formulas for the limits:


And if we find the lower limt we got:


So then the left boundary for this case would be 3 days
Answer:
<em>The greatest number of song he can practice in a week is 2.</em>
Step-by-step explanation:
Suppose, the greatest number of song he can practice in a week is 
He practices each song for
hours. So, the total time required for practicing
number of songs
hours.
Given that, he practices his guitar for 9 hours each week.
So, the equation will be......

<em>(Rounded as the greatest whole number)</em>
Thus, the greatest number of song he can practice in a week is 2.
Tan x =opposite/ adjacent =9/5
x= arctan(9/5)≈61