There is an auditorium with 25 rows of seats there are 10seat in the first row, 12 in the second row, 14 seat in the third row and so on. find the number of saets in the 20th row and also find how many total seat are ther in the auditorium?

By Alexandra

Step-by-step explanation:We can solve this question by arithmetic progressive

a = t1 = 10

d = 2

n = 20

by formula i.e. tn = a + ( n – 1 ) d

therefore t20 = 10 + ( 20 – 1 ) × 2

t20 = 10 + 19 × 2

t20 = 29 × 2

t20 = 48.

therefore there are 48 seats in the 20th row

by the same formula

t25 = 10 + (25 – 1 ) × 2

t25 = 10 + 24 × 2

t25 = 34 × 2

t25 = 68

therefore there are 68 seats in the auditorium