12 minutes
The problem asks us to determine the total time required to arrange four distinct puzzle books on a shelf in every possible order. We are given that each unique arrangement takes 30 seconds to complete.
To find out how many different ways the four books can be arranged, we need to calculate the number of permutations of these four books. The formula for permutations of 'n' distinct items is \(n!\) (n factorial).
In this case, we have 4 books, so \(n=4\). The total number of possible arrangements is:
\(4! = 4 \times 3 \times 2 \times 1\)
Calculating this value:
\(4! = 24\)
This means there are 24 different ways to arrange the four puzzle books on the shelf.
We know that each of these 24 arrangements takes 30 seconds. To find the total time, we multiply the number of arrangements by the time taken for each arrangement.
Total Time (in seconds) = Number of Arrangements \(\times\) Time per Arrangement
\(\text{Total Time} = 24 \times 30 \text{ seconds}\)
\(\text{Total Time} = 720 \text{ seconds}\)
The question asks for the time in minutes. Since there are 60 seconds in one minute, we need to convert the total time from seconds to minutes.
Total Time (in minutes) = Total Time (in seconds) \(\div\) 60
\(\text{Total Time} = \frac{720 \text{ seconds}}{60 \text{ seconds/minute}}\)
\(\text{Total Time} = 12 \text{ minutes}\)
Therefore, it will take 12 minutes to arrange all four puzzle books in every possible order.
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