A student found that the cost of fixed line phones calls to one location from her home followed a linear model. The cost of a 10 minute call is $1.50 while the cost of a 20 minute call was $2.80.
a) Graph on the number plane the cost of a call ($) verses the time taken. State and use a scale.
b) Find the gradient and interpret it in terms of the model.
c) Find the vertical intercept and interpret its meaning.
d) Find the equation of the model.
The speed of sound in dry air at 200 C and 1 atmosphere of pressure is 343 m/s. The speed of sound in steel at 200 C is 5100 m/s.
a) A measuring device tied to a railway track detects the sound of a train whistle in the steel 2 seconds before it detects the sound in the air.
How far away was the train when the whistle blew?
b) The train is travelling at 35 m/s. How far away was the train when the device detected the whistle in the air?
The points: A(0,0) B(3,4) C(8,0) form a triangle.
a) Find the exact length of AB.
b) Find the equation of AB.
c) Find the perpendicular distance from C to the line AB.