[填空题]
The average petrol price, P, in ln3h 7ql);m2l v,bu(rq 3 egkacents per litre, in Australia 20192019ko5v)sbkap(t:v 1x ) s can be modelled by kvo ssv)a (x1bk 5t)p:the function
P(t)=asin($10^{\circ}C$$\times$t)+b,0≤t≤365,where t is the elapsed time, in days, since New Year's Eve 20182018.
Part of the graph of y=P(t) is shown below.
1.Write down the value of b.
The average price of petrol on the 21st of January,2019 was 139139 cents per litre.
2.Show the value of a is equal to 12.
3.Hence calculate:
(1)the average petrol price on the 1010th of February, 2019; P ≈ cents per litre
(2)the minimum and maximum average prices of petrol in Australia 2019.
The cycle of average petrol prices repeats every T days.$P_{min}$ ≈ cents per litre ; $P_{max}$ ≈ cents per litre
3.Determine the value of T.
