When there is a 20.1 mihr wind, an airplane can fly 630 mi with the wind in the same time that it can fly 521 mi against the wind. Find the speed of the plane when there is no wind.

the speed of the plane when there is no wind is 212.25 mi/hr

Step-by-step explanation:

Let v represent the speed of the plane without wind.

Wind speed = 20.1 mi/hr

The resultant speed with wind is;

v + 20.1 mi/hr

The resultant speed against wind is;

v - 20.1 mi/hr

Let t represent the time for the travel.

With wind;

(v+20.1)t = 630 1

Against wind;

(v-20.1)t = 521 2

Divide equation 1 by 2

(v+20.1)/(v-20.1) = 630/521

Cross multiply;

521(v+20.1) = 630(v-20.1)

Collecting like terms;

v(630-521) = 20.1(630+521)

v = 20.1(1151)/109

v = 212.25 mi/hr

the speed of the plane when there is no wind is 212.25 mi/hr

entering that problem on the tube might get you an answer

- "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."