NIMCET 2008 Question Paper with solutions

Question : 76 of 120

Marks: +1, -0

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

Validate

Solution:

x

is the number of rows, then if number of children in last row is

y

, then

y+(y+3)+(y+6)+. . .+\{y+3(x-1)\}=630

⇒ x y+\;{3(x-1)(x)}/{2}=630

x=3 ⇒ 3 y+9=630

(possible,

y=207

x=4 ⇒ 4 y+18=630

(possible,

y=153

x=5 ⇒ 5 y+30=630

(possible,

y=120)

x=6 ⇒ 6 y+45=630

(impossible)

Go to Question:

Prev Question

Next Question