+77
The probability of a fine day is 3/7 and the probability of a wet day is 4/7.
If it is a fine day:
The probability that a man cycles to work is 7/10.
The probability that a man drives to work is 2/10.
The probability that a man takes the train to work is 1/10.
If it is a wet day:
The probability that a man cycles to work is 1/9.
The probability that a man drives to work is 5/9.
The probability that a man takes the train to work is 3/9.
If he works 315 days a year, how many days is he likely to drive to work?
+9673 Let P(E) denote the probability of event E happening.
P(He drives to work)
\(=\dfrac{3}{7}\times \dfrac{2}{10}+\dfrac{4}{7}\times \dfrac{5}{9}\\ =\dfrac{127}{315}\)
therefore number of days he is likely to drive to work = 315 x 127/315 = 127 days. :D
~The smartest cookie in the world.
