Question

An Auditorium has 20 rows of seats. The front row has 45 seats. Each row after that has 4 more seats than the previous row. FInd the total Number of seats in the auditorium.
!!!!Please need help idk how to do this plz!!!

Answer 1

It's a arimethic series question.

Answer 2

\[S _{n}=n/2(t _{1}+t _{n})\]

Answer 3

\[t _{n}=t _{1}+(n-1)d\]

Answer 4

1st row = 45 seats. Common difference is 4.

Answer 5

The 20th term,

Tsubscript(20) = 45 + (20-1)4

Tsubscript(20) = 121.

Back to series formula

Tsubscript(20) = 20/2(45+121)

= 1660 total seats.

@torken8

Answer 6

@torken8 Am I right?

Answer 7

yea thx much man