A small concert hall has $14$ rows of seats. The f... | Free GMAT Practice Question | GMAT Panda

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A small concert hall has 14 rows of seats. The first row contains 12 seats, the second row contains 15 seats, and each subsequent row contains 3 more seats than the previous row. What is the total number of seats in the concert hall?

Explanation	Calculations	Help
$We find how many rows there are from row two through row fourteen inclusive using the Counting Evenly Spaced Integers Rule .$	$\frac{14 - 2}{1} + 1 = 13$	Theory & Tactics Method Card EVEN1-B Click to view full details
$We find the number of seats in the fourteenth row by starting with the 15 seats in row two and adding 3 seats for each of the 12 increases.$	$15 + 12 \times 3 = 51$
$We add the seats in rows two through fourteen using the Sum of Evenly Spaced Integers Rule .$	$\frac{13}{2} \times (15 + 51) = \frac{13}{2} \times 66 = 13 \times 33 = 429$	Theory & Tactics Method Card EVEN1-D Click to view full details
$We find the total seats by adding the seats in row one to the seats in rows two through fourteen.$	$12 + 429 = 441$

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C

A small concert hall has 14 rows of seats. The first row contains 12 seats, the second row contains 15 seats, and each subsequent row contains 3 more seats than the previous row. What is the total number of seats in the concert hall?

Explanation	Calculations	Help
$We find how many rows there are from row two through row fourteen inclusive using the Counting Evenly Spaced Integers Rule .$	$\frac{14 - 2}{1} + 1 = 13$	Theory & Tactics Method Card EVEN1-B Click to view full details
$We find the number of seats in the fourteenth row by starting with the 15 seats in row two and adding 3 seats for each of the 12 increases.$	$15 + 12 \times 3 = 51$
$We add the seats in rows two through fourteen using the Sum of Evenly Spaced Integers Rule .$	$\frac{13}{2} \times (15 + 51) = \frac{13}{2} \times 66 = 13 \times 33 = 429$	Theory & Tactics Method Card EVEN1-D Click to view full details
$We find the total seats by adding the seats in row one to the seats in rows two through fourteen.$	$12 + 429 = 441$

Scroll horizontally to view all columns

C