Can someone help me with this problem thanks.

George estimates that there is a 30% chance of rain the next day if he waters the lawn, a 40% chance if he washes the car, and a 50% chance if he plans a trip to the beach. Assuming George's estimates are accurate, what are the odds

a) in favour of rain tomorrow if he waters the lawn?

b) in favour of rain tomorrow if he washes the car?

c) against rain tomorrow if he plans a trip to the beach?

Answers:

a) 3:7
b) 2:3
c) 1:1

The answers you gave are good. Did you mean that you don't know how to get there?

a) The probability is 30% = 30/100 = 3/10.

Now, the probability that there will be no rain is (10 - 3)/10 = 7/10.

The odd here is 3 : 7, by putting the wanted probability first;

3/10 : 7/10 = 3:7

Can you solve the others now?