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:
an = a1 + (n – 1)d
A(7) = 100 + (7-1) 20
A(7) = 100 + (6)20
A(7) = 100 + 120
A(7) = 220
So, on the 7th night, there 220 patrons.
