EduNinja

[Maximum number: 5]

A marathon is a race over a distance of 42.19 km .

(a)

Find the week during which Rolando runs 42 km .

[ 3 ]

METHOD 1 attempt to substitute into arithmetic sequence formula
$42=6+(n-1) \times 2$ OR 42=2 n+4
( n= ) 19

METHOD 2
list of any consecutive terms ending on/above 42
at least two correct terms (not including 6, 8 and 10)
( n= ) 19

(b)

Find the total distance that Rolando runs in the first 10 weeks.

Davi runs 3 km in the first week. In each subsequent week he runs 20 % further than the previous week. These distances form the terms of a geometric sequence.

[ 2 ]

METHOD 1
$\left(S_{10}=\right) \frac{10}{2}(2 \times 6+(10-1) 2)$ $150(\mathrm{~km})$

METHOD 2
summing (some) correct terms up to 24 OR list of correct cumulative values $6+8+10+\ldots+24$ OR $6,14,24,36 \ldots$ $150(\mathrm{~km})$

IB Maths AI SL 1.2 Arithmetic Sequences and Series Topic Practice

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IB Maths AI SL 1.2 Arithmetic Sequences and Series Topic Practice

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Question 1

Question (a)

Question (b)