First slide

Permutations

Question

From 6 different novels and 3 different dictionaries, 4 novels and I dictionary are to be selected and arranged in a row on a self so that the dictionary is always in the middle. The number of such arrangement is

Moderate

A

less than 500
B

at least 500 but less than 750
C

at least 750 but less than 1000
D

at least 1000

Solution

Required number of ways is $^{6} C_{4} \times^{3} C_{1} \times 4! = 1080$
Clearly, it is more than 1000. So, option $(d)$ is correct

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