Answer: 330
Step-by-step explanation:
We can describe the multiples of 3 from 15 to 45 as an arithmetic sequence with a common difference of 3 and has 11 terms. We can get the answer by using the arithmetic series formula.
Solution:
[tex]S_{n} = \frac{n}{2} [2a_{1} + (n-1)d]\\ S_{11} = \frac{11}{2} [2(15) + (11-1)(3)]\\ S_{11} = \frac{11}{2} [30 + (10)(3)]\\ S_{11} = \frac{11}{2} (30 + 30)\\ S_{11} = \frac{11}{2} (60)\\ S_{11} = \frac{660}{2} \\ S_{11} = 330[/tex]
#ShareYourKnowledge
