A group of 630 children is arranged in rows for a group photograph session Each row contains t...........

Quantitative Aptitiude (CLAT) Probability

A group of 630 children is arranged in rows for a group photograph session. Each row contains three fewer children than the row in front of it. What number of rows is not possible?

Explanation:

Let number of students in front row = x
Then, number of students in next rows will be (x-3), (x-6), ... as we go back.
If number of rows = 3x+(x-3)+(x-6)
=6303x=639x=213
PossibleIf number of rows = 4x+(x-3)+(x-6)+(x-9
)=6304x=648x=162
PossibleIf number of rows = 5x+(x-3)+(x-6)+(x-9)+(x-12)
=6305x=660x=132
PossibleIf number of rows = 6x+(x-3)+(x-6)+(x-9)+(x-12)+(x-15)
=6306x=675
x is not a natural number,
In this case.therefore, 6 rows is not possible.