SOLUTION: The Greek theater has 50 seats in the first row. Each row behind the first-row gains 4 additional seats. How many seats are there in the 10th row?
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Question 1186206: The Greek theater has 50 seats in the first row. Each row behind the first-row gains 4 additional seats. How many seats are there in the 10th row? Answer by ikleyn(52781) (Show Source):
Simply, you should add 9 times 4 seats to 50 seats
the number of seats in 10th row = 50 + 4*9 = 50 + 36 = 86.
The sequence of numbers, presenting seats in each row is
50. 54, 58, 62, . . .
each time you add 4 seats to the previous number.
It is so called arithmetic progression.
Its first term is 50. Its common difference is 4.
The formula for the n-th term is = .
For the 10th term (10th row) you have, according the formula, = 50 + 4*(10-1) = 86,
exactly the same number as we obtained above.
