QUESTION

CSAT

Easy

Maths

Prelims 2023

40 children are standing in a circle and one of them (say child-1) has a ring. The ring is passed clockwise. Child-1passes on the child-2, child-2 passes on to child-4, child-4 passes on to child-7 and so on. After how many such changes (including child-1) will the ring be in the hands of child-1 again?

Select an option to attempt

Explanation

According to the question, the ring is passed clockwise starting from child 1, then child 2, then child 4, then child 7, and so on.

Therefore, the series is formed by adding +1+1, +2+2, +3+3, +4+4, +5+5, +6+6, +7+7, \ldots \ldots \ldots \ldotsand so on.

So, the series is: 1 2 4 7 11 16 22 29 37 6 16 27 39 12 26 1

So, after 15 changes the ring will again be in the hands of child 1.

Hence, option (B) is correct.

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