An auditorium has 51 rows of seats. The first row contains 70 seats. As you move to the rear of the auditorium, each row has 6 more seats than the previous row. 1. How many seats are in row 12 ,136?
2. How many seats are in the auditorium?

seats are in row 12 is 136

seats are in row 136 is 880

seats are in the auditorium is 1071000

Step-by-step explanation:

given data

rows of seat = 51

first row seats =  70

each row seats = 6

to find out

How many seats are in row 12 ,136 and How many seats are in the auditorium

solution

it is AP as 70 , 76 , 82, 88 ............

here A = 70 , d = 6

for n = 12 and 136

so An = a + (n-1)d       .........1

A(12) = 70 + (12-1)6

A(12) = 136

and

A(136) = 70 + (136-1)6

A(136) = 880

and

for total seat we get here Sn for 51 row

Sn = × [ 2a(n-1)d]     ...........2

put here value

Sn = × [ 2(70)(51-1)6]  

Sn = 1071000

the answer is -1 for this question

step-by-step explanation: