GMAT Word Problems Explained — A certain drive-in movie theater has a total of 17 rows of

A certain drive-in movie theater has a total of 17 rows of parking spaces. There are 20 parking spaces in the first row and 21 parking spaces in the second row. In each subsequent row there are 2 more parking spaces than in the previous row. What is the total number of parking spaces in the movie theater?

sequences & seriesword problemssums of integers

Explanation	Calculations	Help
$We determine the number of rows from the second to the seventeenth inclusive.$	$17 - 2 + 1 = 16$	Theory & Tactics Method Card EVEN1-B Click to view full details
$We compute the number of spaces in the seventeenth row by adding the common difference of 2 fifteen times to the second row count.$	$21 + 15 \times 2 = 51$	Theory & Tactics Method Card EVEN1-B Click to view full details
$We sum the parking spaces from the second through the seventeenth row as an arithmetic series.$	$\frac{16}{2} \times (21 + 51) = 8 \times 72 8 \times 72 = 576$	Theory & Tactics Method Card EVEN1-D Click to view full details
$We add the number of spaces in the first row to the sum from the second through the seventeenth row to get the total.$	$20 + 576 = 596$

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