thanks, here is the hard part:
Two letters are posted first class in different towns.
Whats is the probability that only one will be delivered in one day?
would this work?
then, 0.7 x 0.3=0.21
0.7 x 0.3=0.21
0.21 + 0.21=0.42??
thanks, here is the hard part:
Two letters are posted first class in different towns.
Whats is the probability that only one will be delivered in one day?
would this work?
then, 0.7 x 0.3=0.21
0.7 x 0.3=0.21
0.21 + 0.21=0.42??
Only one letter means it could be either one.
That's the idea
Notice that all probabilities sum to 1.
Both letters arrive in 1 day is (0.7)(0.7)=0.49
Neither arrive in a day is (0.3)(0.3)=0.09