Answer:
- train: 40 kph
- plane: 140 kph
Step-by-step explanation:
Let t represent the speed of the train in km/h. Then 4t-20 is the speed of the plane. Travel times are the same, so we can use the formula ...
time = distance/speed
and equate the travel times.
110/t = 385/(4t-20)
Cross multiplying gives ...
110(4t -20) = 385t
440t -2200 = 385t . . . . . eliminate parentheses
55t -2200 = 0 . . . . . . . . . subtract 385t
t -40 = 0 . . . . . . . . . divide by 55
t = 40 . . . . . . . . . . . add 40; train's speed is 40 kph
4t -20 = 140 . . . . . . find plane's speed; 140 kph
The train's speed is 40 km/h; the plane's speed is 140 km/h.
_____
<em>Check</em>
Train's travel time = 110 km/(40 km/h) = 2.75 h.
Plane's travel time = 385 km/(140 km/h) = 2.75 h.
C I’m not sure but I hope it helps
Answer:
D. A value of 0.9 is more than 2 standard deviations from the mean.
Step-by-step explanation:
A is wrong, because the standard deviation is +/-0.15 (the measure up or down from the mean)
B is wrong, because the mean is exactly 0.5
C is wrong, because 1 standard deviation up from the mean is 0.65, and 0.7 is outside of that.
Answer:
9.
Step-by-step explanation:
36 * 1/4
= 36/4
=9.
