Exercises for Question Type 6: Finding sum of first n terms given the values of other sums - IB | RevisionDojo

Question Type 6: Finding sum of first n terms given the values of other sums Exercises

Question 1

The sum of the first 5 terms of an arithmetic sequence is 20 and the sum of the first 8 terms is 44.

Find the sum of the first 6 terms.

[7]

Question 2

The sum of the first 9 terms of an arithmetic sequence is 81 and the sum of the first 12 terms is 132. Find the sum of the first 15 terms.

[7]

Question 3

Given the sum of the first 4 terms is 14 and the sum of the first 7 terms is 35 for an arithmetic sequence, find the sum of the first 10 terms.

[6]

Question 4

The sum of the first 5 terms of an arithmetic sequence is 35 and the sum of the first 9 terms is 99. Find the sum of the first 7 terms.

[8]

Question 5

Given that $S_8=96$ and $S_3=21$ for an arithmetic sequence, find $S_6$ .

[6]

Question 6

For an arithmetic sequence, the sum of the first 7 terms is 56 and the sum of the first 3 terms is 18. Find the sum of the first 5 terms.

[6]

Question 7

The sum of the first 4 terms of an arithmetic sequence is 20 and the sum of the first 6 terms is 42.

Find the sum of the first 8 terms.

[7]

Question 8

Given that $S_{10}=150$ and $S_{6}=66$ for an arithmetic sequence.

Find $S_{4}$ . [6 marks]

[6]

Question 9

Given the sum of the first 8 terms is 40 and the sum of the first 14 terms is 91 for an arithmetic sequence, find the sum of the first 20 terms.

[7]