Testbook Test series

Question

In how many ways we can wear 4 distinct rings in 3 particular fingers?

Comments

81 ways

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How??please Explain.

Answer 1

it says 4 different rings in 3 particular finger.

means that have put condition on fingers as they have given 3 fingers to put rings at. (so we dont need to worry about selecting 3 from 10 fingers)

.

(in such questions always fix the non movable object (here this is fingers))

so first ring can be put in any of the 3 fingers in 3 ways.

similarly second ring in 3 ways 

.third ring in 3 ways

fourth ring in 3 ways

so ultimately 4 rings can be wore in  3*3*3*3  ways = 81 ways solution.

Comments

A particular finger may have two rings as well.what about that?

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see i have all the cases in which a finger can have o or 1 or 2 or 3 or 4 rings. here 

if u break it u will find its arrangement of n different things into r different boxes.