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Find the value of the following expression and round to the nearest integer:

sum_(n=2)^(25)900(1.21)^(n-1)
Answer:

Find the value of the following expression and round to the nearest integer:\newlinen=225900(1.21)n1 \sum_{n=2}^{25} 900(1.21)^{n-1} \newlineAnswer:

Full solution

Q. Find the value of the following expression and round to the nearest integer:\newlinen=225900(1.21)n1 \sum_{n=2}^{25} 900(1.21)^{n-1} \newlineAnswer:
  1. Recognize Given Expression: Recognize that the given expression is a geometric series where the first term a=900(1.21)21=900(1.21)a = 900(1.21)^{2-1} = 900(1.21), the common ratio r=1.21r = 1.21, and the number of terms n=252+1=24n = 25 - 2 + 1 = 24.
  2. Use Formula for Sum: Use the formula for the sum of a finite geometric series, which is Sn=a(1rn)/(1r)S_n = a(1 - r^n) / (1 - r), where SnS_n is the sum of the first nn terms of the geometric series.
  3. Plug Values into Formula: Plug the values into the formula: S24=900(1.21)(11.2124)/(11.21)S_{24} = 900(1.21)(1 - 1.21^{24}) / (1 - 1.21).
  4. Calculate Numerator: Calculate the numerator of the fraction: 11.21241 - 1.21^{24}. This requires calculating 1.21241.21^{24} first.\newline1.2124799.531.21^{24} \approx 799.53 (using a calculator)\newlineNow, subtract this from 11: 1799.53798.531 - 799.53 \approx -798.53.
  5. Calculate Denominator: Calculate the denominator of the fraction: 11.21=0.211 - 1.21 = -0.21.
  6. Divide Numerator by Denominator: Now, divide the numerator by the denominator: 798.53/0.213802.52-798.53 / -0.21 \approx 3802.52.
  7. Multiply by First Term: Multiply this result by the first term of the series 900×1.21900 \times 1.21 to get the sum of the series: 3802.52×900×1.214142712.123802.52 \times 900 \times 1.21 \approx 4142712.12.
  8. Round to Nearest Integer: Round the result to the nearest integer: 4142712.124142712.12 rounds to 41427124142712.

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