On1

1

day in1000

1000

, there is a fire and the fire alarm rings.

On1

1

day in100

100

, there is no fire and the fire alarm rings (false alarm)

On1

1

day in10

,

000

10,000

, there is a fire and the fire alarm does not ring (defective alarm).

On9

,

889

9,889

days out of10

,

000

10,000

, there is no fire and the fire alarm does not ring.

If the fire alarm rings, what is the (conditional) probability that there is a fire?

Writtenp

(

p(

there is a fire | fire alarm rings)

)