3 Consider the geometric series: \( 45+15+5+\ldots \) 3.1 Does the sequence converge or diverge? Justify your answer. 3.2 Determine the sum to infinity of the series, if it exists.
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The sequence converges because the absolute value of the common ratio \( r \) is less than 1. In this series, the first term \( a = 45 \) and the common ratio can be found by dividing the second term by the first, \( r = \frac{15}{45} = \frac{1}{3} \). Since \( |r| < 1 \), the geometric series converges. The sum to infinity of a converging geometric series can be calculated using the formula \( S = \frac{a}{1 - r} \). Here, \( S = \frac{45}{1 - \frac{1}{3}} = \frac{45}{\frac{2}{3}} = 45 \times \frac{3}{2} = 67.5 \). Thus, the sum to infinity is 67.5.