3x + y = 3
7x + 2y = 1
First isolate one of the variables (x or y) in one of the equations.
Isolate "y" in the first equation(because it is the easiest to isolate) and substitute it into the second equation.
3x + y = 3 Subtract 3x on both sides
3x - 3x + y = 3 - 3x
y = 3 - 3x
7x + 2y = 1
7x + 2(3 - 3x) = 1 [since y = 3 - 3x, you can substitute (3-3x) for "y"]
Multiply/distribute 2 into (3 - 3x)
7x + (3(2) - 3x(2)) = 1
7x + 6 - 6x = 1
x + 6 = 1 Subtract 6 on both sides
x = -5
Now that you know "x", substitute it into one of the equations (I will do both)
3x + y = 3
3(-5) + y = 3 [since x = -5, you can plug in -5 for "x"]
-15 + y = 3 Add 15 on both sides
y = 18
7x + 2y = 1
7(-5) + 2y = 1
-35 + 2y = 1 Add 35 on both sides
2y = 36 Divide 2 on both sides
y = 18
x = -5, y = 18 or (-5, 18)
It's easy you just need to multiply both numbers by 25
Answer: The running time should at least 119.32 seconds to be in the top 5% of runners.
Step-by-step explanation:
Let X= random variable that represents the running time of men between 18 and 30 years of age.
As per given, X is normally distrusted with mean 
and standard deviation 
.
To find: x in top 5% i.e. we need to find x such that P(X<x)=95% or 0.95.
i.e. 
Since, z-value for 0.95 p-value ( one-tailed) =1.645
So,
Hence, the running time should at least 119.32 seconds to be in the top 5% of runners.
Answer:
it is 6!/8!
because you take the first and second place you take it as a whole team, and divided by all the cases
