A large auditorium had 64 rows with 52 seats in
each row in the balcony and 123 rows with 78 seats
in each row at the ground level. How many people
in all can sit in the auditorium?
Answers
Answer :
The number of seats in the first row of an auditorium is 18 and the number of seats in each row thereafter is 2 more than in the previous row. What is the total number of seats in the rows of the auditorium?
The number of seats in the first row is 18;
The number of seats in the second row is 18+2=20;
The number of seats in the third row is 18+2*2=22;
The number of seats in the fourth row is 18+3*2=24;
...
The number of seats in the nth row is 18+(n-1)*2.
Notice that if we knew the total number of rows we would be able to sum the number of seats in each row and get the total number of seats.
(1) The number of rows of seats in the auditorium is 27. Sufficient.
(2) The number of seats in the last row is 70 --> 18+(n-1)*2=70, where n is the number of rows. We can get n. Sufficient.