Q6 of 140 Page 288

If 15Pr–1 : 16Pr–2, = 3 : 4, find r.

To find: the value of r


Formula Used:


Total number of ways in which n objects can be arranged in r places (Such that no object is replaced) is given by,


nPr


15Pr–1 : 16Pr–2, = 3 : 4











Since r cannot be 21 as it creates a negative factorial in denominator. Therefore,
 is not possible.


Hence, value of r is 14


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