There are 25 rows of seats in an auditorium. The 1st row in of 20 seats, the 2nd row of 22 seats and so on. How many seats are there in the 21st row?
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60 seats in 21st row.
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Answer: 60
Step-by-step explanation:
Answer: 60.
Step-by-step explanation:
The number of seats will be in the following order-
20, 22, 24,.........
It clearly forms an arithmetic sequence.
From the question, you have
a= 20 (first term), d= 2 (common diff)
n=21 (asked) , t21=?
The formula of general term is
tn = a+(n-1)d
t21 = 20+(21-1)2
= 20+ (20)2
= 20+40
= 60.
Hope I helped you!
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