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:
1
Step-by-step explanation:
.020 because it is 2 spots behind the decimal
Answer:
The fourth pair of statement is true.
9∈A, and 9∈B.
Step-by-step explanation:
Given that,
U={x| x is real number}
A={x| x∈ U and x+2>10}
B={x| x∈ U and 2x>10}
If 5∈ A, Then it will be satisfies x+2>10 , but 5+2<10.
Similarly, If 5∈ B, Then it will be satisfies 2x>10 , but 2.5=10.
So, 5∉A, and 5∉B.
If 6∈ A, Then it will be satisfies x+2>10 , but 6+2<10.
Similarly, If 6∈ B, Then it will be satisfies 2x>10 , and 2.6=12>10.
So, 6∉A, and 6∈B.
If 8∈ A, Then it will be satisfies x+2>10 , but 8+2=10.
Similarly, If 8∈ B, Then it will be satisfies 2x>10. 2.8=16>10.
So, 8∉A, and 8∈B.
If 9∈ A, Then it will be satisfies x+2>10 , but 9+2=11>10.
Similarly, If 9∈ B, Then it will be satisfies 2x>10. 2.9=18>10.
So, 9∈A, and 9∈B.
