Q. Find the value of the following expression and round to the nearest integer:n=1∑20600(0.91)n+1Answer:
Recognize Problem Type: Recognize that the given expression is a geometric series where the first term a1 is 600(0.91)2, the common ratio r is 0.91, and the number of terms n is 20.
Use Geometric Series Formula: Use the formula for the sum of a finite geometric series, which is Sn=a1(1−rn)/(1−r), where Sn is the sum of the first n terms.
Calculate First Term: Calculate the first term a1 by substituting n=1 into the expression, which gives us a1=600(0.91)2.a1=600×(0.91)2a1=600×0.8281a1=496.86
Calculate Sum S20: Calculate the sum S20 using the formula from Step 2 with a1=496.86, r=0.91, and n=20.S20=496.86×(1−(0.91)20)/(1−0.91)
Calculate (0.91)20: Calculate (0.91)20 to find the value that will be subtracted from 1 in the numerator of the sum formula.(0.91)20≈0.151356
Substitute Value: Substitute the value from Step 5 into the sum formula to calculate S20. S20=496.86×(1−0.151356)/(1−0.91)S20=496.86×(0.848644)/0.09
Perform Calculations: Perform the calculations to find the sum S20. S20=496.86×0.848644/0.09S20=421.788/0.09S20=4686.53333333
Round to Nearest Integer: Round the sum S20 to the nearest integer.S20≈4687
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