Q. Find the sum of the first 10 terms of the following series, to the nearest integer.15,30,60,…Answer:
Identify type of series: Identify the type of series.The given series is geometric because each term is multiplied by a common ratio to get the next term.
Determine common ratio: Determine the common ratio r of the series.To find the common ratio, divide the second term by the first term.1530=2Common Ratio r: 2
Use formula for sum: Use the formula for the sum of the first n terms of a geometric series.The formula for the sum of the first n terms (Sn) of a geometric series is:Sn=a⋅(1−rn)/(1−r), where a is the first term and r is the common ratio.
Plug values into formula: Plug the values into the formula to find the sum of the first 10 terms.a=15 (the first term)r=2 (the common ratio)n=10 (the number of terms)S10=15×(1−210)/(1−2)
Calculate sum: Calculate the sum using the values from Step 4.S10=15×(1−1024)/(1−2)S10=15×(−1023)/(−1)S10=15×1023S10=15345
Round sum: Round the sum to the nearest integer. The sum is already an integer, so no rounding is necessary.