A new night club opens. The first night 100 patrons attend. For each successive night for a month, 20 more attend. How many attend on the 7th night?
Arithmetic sequence formula finding the nth number:
<span>a</span><span>n</span><span> = a</span><span>1</span><span> + (n – 1)d</span>
<span>A(7) = 100 + (7-1) 20</span>
<span>A(7) = 100 + (6)20</span>
<span>A(7) = 100 + 120</span>
<span>A(7) = 220</span>
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<span>So, on the 7th night, there 220 patrons.</span>
