Originally Posted by
Line7
This is the other problem I need to solve, any insight on how to do it? Thanks for the help!
Monthly rainfalls in a tropical city are independents and normally distributed with an average of 60 cm and variance of 25 cm2, N(60,5). There is flood in the city if monthly rainfall exceeds 75 cm.
(a)What is the probability of having less than 50 cm?
(b)What is the probability of occurrence of flood?
(c)What is the probability that monthly rainfall exceeds 50 and no flood occurs?
(d)What will be the maximum monthly rainfall if probability of occurrence is 90%?
ok, this problem is relatively easy. I won't give solutions but I'll explain how to solve (I dont have the means or time to make calculations).
You first should graph what you have. You know its normally distributed, with a mean and a variance. Excel, Matlab, etc. can draw this graph for you.
a. the probability of having less than 50 is done by summing all the points from 50-inf and subtract that result from 1 (which is the area under the entire curve) and you'll get the probability for LESS than 50.
b. For a flood, you just sum from 75, inf and use that as the probability.
c. here you calculate probability from 50 to inf and subtract 75 to inf.
d. here you solve for when the probability is .9 (somewhere to the right of the mean)