Matt and anna killian are frequent fliers on fast-n-go airlines. they often fly between two cities that are a distance of 1980 miles apart. on one particular trip, they flew into the wind and the trip took 5.5 hours. the return trip with the wind behind them, only took about 4.5 hours. find the speed of the wind and the speed of the plane in still air.

y (plane speed) 400 miles/hr

x (wind speed)  40 miles/hr

Step-by-step explanation:

going into the wind make the plane flew 5,5 hours to get 1980 miles, implies the real travel speed was

1980 / 5,5 = 360 miles/hours, and at the same time is the result of:  

speed plane (y)  in direction A to B  plus wind speed (x) in direction B to A. Notice opposites direction speed, so we have:

y + (-x) = 360          (1)

The return fly  took 4,5 hours so 1980/4,5 = 440 miles/ hours as the result

Y + x = 440             (2)

We have a two equation with two variables system, It could be solved for any of the procedures. We will use the substitution method.

From equation      (1)        y + (-x) = 360         y  - x = 360      y = 360 + x    (1)

In the second equation    

y + x = 440         then we replace y for its value as function of x

(360 + x ) + x = 440

Solving for x        360 + 2x = 440      or    2x = 440 – 360        

 x   (440 - 360)/2

 x = 40 miles/hr

 X (wind speed ) = 40 miles/hr

And replacing the value of x in eq. (1)        y = 360 + 40 = 400

Y (plane speed) = 400 miles /hr

yes

step-by-step explanation:

"it's not the heat, it's the humidity".   that's a partly valid phrase you may have heard in the summer, but it's actually both.   the heat index, also known as the apparent temperature, is what the temperature feels like to the human body when relative humidity is combined with the air temperature.   this has important considerations for the human body's comfort.   when the body gets too hot, it begins to perspire or sweat to cool itself off.   if the perspiration is not able to evaporate, the body cannot regulate its temperature.   evaporation is a cooling process.   when perspiration is evaporated off the body, it effectively reduces the body's temperature.   when the atmospheric moisture content (i.e. relative humidity) is high, the rate of perspiration from the body decreases.   in other words, the human body feels warmer in humid conditions.   the opposite is true when the relative humidity decreases because the rate of perspiration increases.   the body actually feels cooler in arid conditions.   there is direct relationship between the air temperature and relative humidity and the heat index, meaning as the air temperature and relative humidity increase (decrease), the heat index increases (decreases).

step-by-step explanation: