Interpret the following sine regression model.
y = 0.884 sin(0.245x - 1.093) + 0.400
what is the value of a in this equation?

The question is incomplete, so I will describe the sine regression model.

The function

y = 0.884 sin(0.245x - 1.093) + 0.400

correspond to the general equation:

y = a sin(bx - c) + d

where:

a = 0.884

b = 0.245

c = 1.093

d = 0.400

The amplitude of the function is computed as follows:

amplitude = |a| = 0.884

The period of the function is computed as follows:

period = 2π/|b| = 25.6456

The phase shift of the function is computed as follows:

phase shift = c/b = 4.4612 to the right (because there is a minus sign before c in the equation)

The vertical shift of the function is computed as follows:

vertical shift = d = 0.400

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."