Date | May 2021 | Marks available | 3 | Reference code | 21M.1.SL.TZ1.8 |
Level | Standard Level | Paper | Paper 1 | Time zone | Time zone 1 |
Command term | Calculate | Question number | 8 | Adapted from | N/A |
Question
Charlie and Daniella each began a fitness programme. On day one, they both ran 500 m. On each subsequent day, Charlie ran 100 m more than the previous day whereas Daniella increased her distance by 2% of the distance ran on the previous day.
Calculate how far
Charlie ran on day 20 of his fitness programme.
Daniella ran on day 20 of her fitness programme.
On day n of the fitness programmes Daniella runs more than Charlie for the first time.
Find the value of n.
Markscheme
attempt to find u20 using an arithmetic sequence (M1)
e.g. u1=500 and d=100 OR u20=500+1900 OR 500, 600, 700, …
(Charlie ran) 2400 m A1
[2 marks]
(r=) 1.02 (A1)
attempt to find u20 using a geometric sequence (M1)
e.g. u1=500 and a value for r OR 500×r19 OR 500, 510, 520.2, …
(Daniella ran) 728 m (728.405…) A1
[3 marks]
500×1.02n-1>500+(n-1)×100 (M1)
attempt to solve inequality (M1)
n>184.215…
n=185 A1
[3 marks]