Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.

Topic: some confusing math probablity problems
Replies: 3   Last Post: Apr 10, 2014 11:06 PM

 Messages: [ Previous | Next ]
 justlooking for someone else Posts: 77 Registered: 12/10/04
some confusing math probablity problems
Posted: Apr 9, 2014 11:13 PM

hi,

There are a couple of math problems in geometric probablity that we
seem to have a problem with. My daughter and I were trying to work
this problem out, but the answer we get is different from what the
suggested answer is in the book.

P1. A bus comes to a station once every 10 minutes and waits at the
station for 1.5 minutes.

question 1. Find the probability that the bus will be at te station
when you arrive (Book answer: 0.15) - (our answer 0.13 - 1.5/11.5)
ours is wrong

question 2. IF you go to the station 20 times, predict about how many
times you will have to wait less than 3 minutes. (book answer: 9
times) - (our answer which is wrong is: (3/11.5) * 20 = 7.xxx)

P2. A radio station gives a weather report every 15 minutes. Each
report lasts 45 seconds. Suppose you turn on the radio at a random
time.

Question 1. Find the probability that you will have to wait more than
5 minutes to hear the weather report

Question 2. If you turn on the radio at 50 random times, predict about
how many times you will hahve to wait less than 1 minute before the
start of the next weather report.

I don't understand how it works obviously. We did other geometric
prob problems, but these two are confusing. Please explain your
answers. I am a little confused myself. thanks

s

Date Subject Author
4/9/14 justlooking for someone else
4/10/14 William Elliot
4/10/14 Stan Brown
4/10/14 justlooking for someone else