Over a 28-day period, the cost per litre of petrol was modelled by c(t)=9.2sin(7π(t−4))+107.8 cents L−1.
(1) True or false?
- “The cost per litre oscillates about 107.8 cents with maximum price 1.17 per litre.”
- “Every 14 days, the cycle repeats itself.”
(2) What was the cost of petrol on day 7, to the nearest tenth of a cent per litre?
(3) On which days was the petrol priced at 1.10 per litre?
(4) What was the minimum cost per litre and when did it occur?