Answer:
A) Rule= 6+(n-1)3
B) row 15 = 102 seats
C). $7800
D). Rule = 7+(n-1)3
Revenue= $8200
Explanation:
A) ..
Row1= 6
Row 2= 9
Row 3 = 12
Common difference d = 9-6= 3
First term a = 6
Rule = a+(n-1)d
Rule= 6+(n-1)3
B) in row 15 n = 15
N(15) = 6+(15-1)3
N(15) = 6+(14)3
N(15) = 6(17)
N(15) = 102
C) summation of seat in the first 10 rows
S= n/2(2a +(n-1)d)
S= 10/2(2*6+(10-1)3)
S= 5(12+27)
S= 5(39)
S= 195
Revenue = 195 seat * $40
=$7800
D).
An extra chair is added to each row
First row now = 7
Second row= 10
Third row = 13
D= 10-7= 3
Rule = a+(n-1)d
Rule = 7+(n-1)3
Sum of first 10 rows again, n= 10
S= n/2(2a +(n-1)d)
S= 10/2(2*7+(10-1)3)
S= 5(14+27)
S= 5(41)
S= 205 seats
Revenue= seats * $40
Revenue= 205 *$40
Revenue= $8200