Find the sum of the first 10 terms of the following sequence. Round to the nearest hundredth if necessary.25,19.5,15.21,…Sum of a finite geometric series:Sn=1−ra1−a1rnAnswer:
Q. Find the sum of the first 10 terms of the following sequence. Round to the nearest hundredth if necessary.25,19.5,15.21,…Sum of a finite geometric series:Sn=1−ra1−a1rnAnswer:
Identify terms and ratio: Identify the first term a1 and the common ratio r of the geometric sequence.The first term a1 is 25. To find the common ratio r, we divide the second term by the first term.r=2519.5
Calculate common ratio: Calculate the common ratio r.r=2519.5r=0.78
Use sum formula: Use the formula for the sum of the first n terms of a geometric series: Sn=1−ra1−a1⋅rn. We have a1=25, r=0.78, and n=10.
Substitute and calculate sum: Substitute the values into the formula and calculate the sum.S10=1−0.7825−25×0.7810
Calculate numerator: Calculate the numerator of the formula.25×0.7810=25×(0.1073741824)≈2.68435456
Subtract to get numerator: Subtract the result from 25 to get the final numerator.25−2.68435456≈22.31564544
Calculate denominator: Calculate the denominator of the formula.1−0.78=0.22
Divide to find sum: Divide the numerator by the denominator to get the sum of the first 10 terms.S10=0.2222.31564544
Perform division: Perform the division to find the sum S10. S10≈101.43429745
Round to nearest hundredth: Round the sum to the nearest hundredth. S10≈101.43
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