The second and third terms of a geometric progression are 48 and 32 respectively. Find the sum to infinity of the progression.
Solution
Let the first term of the geometric progression be \(a\) and the common ratio be \(r\).
The second term is given by \(ar = 48\).
The third term is given by \(ar^2 = 32\).
Dividing the third term by the second term gives:
\(\frac{ar^2}{ar} = \frac{32}{48}\)
\(r = \frac{2}{3}\)
Substitute \(r = \frac{2}{3}\) into \(ar = 48\):
\(a \left( \frac{2}{3} \right) = 48\)
\(a = 72\)
The sum to infinity of a geometric progression is given by:
\(S_\infty = \frac{a}{1 - r}\)
Substitute \(a = 72\) and \(r = \frac{2}{3}\):
\(S_\infty = \frac{72}{1 - \frac{2}{3}} = \frac{72}{\frac{1}{3}} = 72 \times 3 = 216\)
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