A geometric sequence has first term 54 and 4th term 2. What is the common ratio?

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Answer 1 · 2015-11-08T09:53:09

#r = 1/3#

#A_n = A_1r^(n - 1)#

#A_1 = 54#

#A_4 = 2 = A_1r^(4 - 1)#

#=> 2 = 54r^3#

#=> 2/54 = r^3#
#=> 1/27 = r^3#

#=> (1/3)^3 = r^3#

#=> r = 1/3#