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Date May 2018 Marks available 3 Reference code 18M.2.hl.TZ1.1
Level HL only Paper 2 Time zone TZ1
Command term Calculate Question number 1 Adapted from N/A

Question

The 3rd term of an arithmetic sequence is 1407 and the 10th term is 1183.

Find the first term and the common difference of the sequence.

[4]
a.

Calculate the number of positive terms in the sequence.

[3]
b.

Markscheme

u1 + 2d = 1407,  u1 + 9d = 1183   (M1)(A1)

u1 = 1471, d = −32     A1A1

[4 marks]

a.

1471 + (n − 1)(−32) > 0      (M1)

n < \(\frac{{1471}}{{32}} + 1\)

n < 46.96…      (A1)

so 46 positive terms      A1

[3 marks]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Topic 1 - Core: Algebra » 1.1 » Arithmetic sequences and series; sum of finite arithmetic series; geometric sequences and series; sum of finite and infinite geometric series.
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