A group of 630 children is seated in rows for a group photo session. Each row contains three less children than the row in front of it. Which one of the following number of rows is not possible?
Explanation & Solution
Correct Option: (D) 6
For n rows, total children = n(first row + last row)/2 = n(2a-(n-1)×3)/2 = 630, where a is first row. Try n=3,4,5,6. Only n=6 gives non-integer solution.
हिंदी में प्रश्न एवं आदर्श उत्तर
A group of 630 children is seated in rows for a group photo session. Each row contains three less children than the row in front of it. Which one of the following number of rows is not possible?
सही उत्तर: (D) 6
For n rows, total children = n(first row + last row)/2 = n(2a-(n-1)×3)/2 = 630, where a is first row. Try n=3,4,5,6. Only n=6 gives non-integer solution.