Question

On the day after a hurricane, 50% of all residents in Florida lived without

electricity, 40% of all residents lived without water, and 20% of all residents

lived with neither electricity nor water.

What is the probability that a randomly selected resident

in Florida had both electricity and water services on that day?

Answer 1

Let , Event A be the all residents in Florida lived without electricity

Event B be the all residents lived without water

Given , P( A ) = 50% = 0.5 , P( B ) = 40% =0.4 , P( A and B ) = 0.2

We have to find shaded area.

P( A or B ) = P( A ) + P( B ) - P( A and B )

P( A or B ) = 0.5+ 0.4 - 0.2 = 0.7

So , probability that a randomly selected resident in Florida had both electricity and water services on that day is ,

= 1 - P( A or B )

= 1 - 0.7

= 0.3 = 30%