maths
posted by Anonymous on .
Andy is not a very good navigator. When he enters a small town, the probability that he gets lost and cannot find the correct road to continue his journey, is 0.2. When he enters a large town, the probability that he does not find the correct exit road is 0.25. He starts on a journey that passes through two small towns followed by one large town. Draw a tree diagram to represent this info and use it to find the probability that
a)he reaches th second small town and leaves it on the correct road
b)he reaches the large town but fails to find the correct exit road.
plz help (any explanations wud be great)

town 1
right .8 wrong .2 (lost)
town 2
right .8 wrong .2 (lost)
city
right .75 wrong .25 (lost)
for part a
branches = right .8 * right .8 so .64
for part b
branches = right .8 * right .8 * wrong .25 so .64/4 = .16