Answer:
r = 225 Mil/h speed of the airplane in still air
Step-by-step explanation:
Then:
d is traveled distance and r the speed of the airplane in still air
so the first equation is for a 4 hours trip
as d = v*t
d = 4 * ( r + 25) (1) the speed of tail wind (25 mil/h)
Second equation the trip back in 5 hours
d = 5 * ( r - 25 ) (2)
So we got a system of two equation and two unknown variables d and
r
We solve it by subtitution
from equation (1) d = 4r + 100
plugging in equation 2
4r + 100 = 5r - 125 ⇒ -r = -225 ⇒ r = 225 Mil/h
And distance is :
d = 4*r + 100 ⇒ d = 4 * ( 225) + 100
d = 900 + 100
d = 1000 miles
Negative numbers. Remember that whole numbers are 0 and positive numbers.
Ohh wow nice, do your own work lazy person
D) 4.5 Standard Deviations Above the Mean
All you have to do is add .2 to 6.6 until you reach 7.5
6.8
7.0
7.2
7.4
Then you only need half of .2 to reach 7.5, so it's 4.5 standard deviations above the mean
