The correct answer among the choices provided is the second option. Events A and B are dependent because P(A|B) P(B). And from conditional probability, we have P(A|B) = P(AintersectionB) / P(B).
Therefore, P (AintersectionB) is equal to P(A|B) × P(B).
Let the slower train's velocity be x-21
Let the faster train's velocity be x
We know that the approach speed is the sum of both speeds, so x+x -21= 2x-21.
The approach rate is given by Distance/time = 471/3 = 157mpH
x+x-21=157
2x=157+21
2x=178
x=89mph
The slower train is travelling 89-21 = 68mph
The faster train is travelling 89mph.
The coefficient of y∧15×∧2 in expansion of (y∧3+x)∧7 is (15×2)+(3×7)= 51
