🚀 go-pugleaf

Craig Lawson <lawso@ozemail.com.au> wrote in article
<01bc1cb4$3383d4e0$27bc07cb@lawso.ozemail.com.au>...
> My name is Quinn Lawson.  I'm currently in grade 12 and my Maths teacher
> has hit me with a relatively confusing question.  I gave it a go but with
> no success.  See if you can help
> 
> A radar operator in a war zone must identify planes as either friendly of
> hostile.  The probability that the radar operator does that correctly is
> 0.8.  Ninety percent of the planes on the war zone are truly friendly. 
> When a plane is identified as hostile, a rocket is launched to shoot it
> down.  Determine the probability that the rocket is launched.
> 'Friendly fire' occurs when a plane is shot down by their own forces. 
The
> probability that a rocket brings down a plane in the war zone is 0.6. 
> Determine the probability that a truly friendly plane is shot down by
> friendly fire.
> 
> If anyone can help it would be greatly appreciated!
> If you can help, explain your answer and Email me at 
lawso@ausemail.com.au
> 
> 
The probability that the radar operator launches a rocket at a:
1) friendly plane is 0.9*(1-0.8)=0.18=18%
2) hostile plane is 0.1*0.8=0.08=8%
A total of 0.18+0.08=0.26=26%

The probability that a truely friendly plane is shot down by friendly fire
is:
0.9*(1-0.8)*0.6=0.108=10.8%