A movie theatre has 30 rows. The first row has 26 seats and as you move to the back each additional row has one seat added. How many seats are in the theatre?
2 answers
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Number of seats in first row = 26
Number of seats in last row = 26+30-1=55
We can find the sum using Gauss's method:
26+27+28+.....+54+55=x
55+54+.....+28+27+26=x
Add the two rows
81+81+.....81 (30 rows) = 2x
30*81 = 2x
x=1215 seats
Number of seats in last row = 26+30-1=55
We can find the sum using Gauss's method:
26+27+28+.....+54+55=x
55+54+.....+28+27+26=x
Add the two rows
81+81+.....81 (30 rows) = 2x
30*81 = 2x
x=1215 seats
4 answers