Use binomial distribution, with p=0.20, n=20, x=3
P(X=x)=C(n,x)p^x (1-p)^(n-x)
P(X>=3)
=1-(P(X=0)+P(X=1)+P(X=2))
=1-(C(20,0)0.2^0 (0.8)^(20-0)+C(20,1)0.2^1 (0.8)^(20-1)+C(20,2)0.2^2 (0.8)^(20-2))
=1-(0.0115292+0.057646+0.136909)
=1-0.206085
=0.793915
Answer:x=1/108 is your answer
-5/6x-1/9x=-102
1/x(-5/6-1/9)=-102
1/x=-102/(-17/18)=-102×-18/17=108
x=1/108
The answer is 220 at least. Here's how it goes
Multiply $205 with 6 and subtract the sum of the five years from it. That's how I think and I hope it helps
We know that
the law of cosines establish
b²=a²+c²-2*a*c*cos B
in this problem
a=4 units
c=5 units
B=60°
so
b²=a²+c²-2*a*c*cos B
b²=4²+5²-2*4*5*cos 60°
b²=16+25-40*(1/2)
b²=16+25-20
b=√[16+25-20]
the answer is
b=√[16+25-20]
