Step-by-step explanation:
12x-15-4x+1=-6
12x-4x= -6+15-1
8x= 8
x=1
my answer is 100 % correct
Answer:
x=8/11
Step-by-step explanation:
10+6/x=22
16/x=22
16=22x
x=16/22
x=8/11
Answer:
The standard deviation of this probability distribution is 1.2.
Step-by-step explanation:
We have that:
P(X = 0) = 0.25
P(X = 1) = 0.3
P(X = 2) = 0.1
P(X = 3) = 0.35
Mean:
Each value multiplied by its probability. So
Variance:
Sum of the squares of the values subtracted from the mean, and multiplied by its probability.

Standard deviation:
Square root of the variance. So

The standard deviation of this probability distribution is 1.2.
Answer:the plane in still air is 904 km/h
the rate of the wind is 104 km/h
Step-by-step explanation:
Let x represent the rate or speed of the plane in still air.
Let y represent the rate or speed of the wind.
Flying against the wind, an airplane travels 4000 kilometers in 5 hours. This means that the total speed of the airplane would be (x - y) km/h
Distance = speed × time
Therefore
4000 = 5(x - y)
4000 = 5x - 5y - - - - - - - - -1
Flying with the wind, the same plane travels 5040 kilometers in 4 hours. This means that the total speed of the airplane would be (x + y) km/h. Therefore,
5040 = 4(x + y)
5040 = 4x + 4y - - - - - - - - - 2
Multiplying equation 1 by 4 and equation 2 by 5, it becomes
16000 = 20x - 20y
20160 = 20x + 20y
Subtracting, it becomes
- 4160 = - 40y
y = - 4160/-40
y = 104
Substituting y = 104 into equation 1, it becomes
4000 = 5x - 5 × 104
4000 = 5x - 520
5x = 4000 + 520
5x = 4520
x = 4520/5 = 904
Answer:
The required drawing showing the cliff, river, and tower as well as the details in the question is attached, please find alongside the answer
The width of the river is approximately 51.55 meters
Step-by-step explanation:
The height of the observation tower = 11 meters
The angle of elevation of the cliff top and the opposite side of the river = 20°
The angle of elevation of the tower top and the opposite side of the river = 30°
Therefore, by sine rule, we have;
h/sin(20) = w/sin(60)
11/sin(10) = length, l/sin(60)
l = sin(60) ×11/sin(10) ≈ 54.86 meters
w = l × cos (20) = 54.86 meters × cos (20) ≈ 51.55 meters
The width, w, of the river is approximately 51.55 meters.