Hi, can someone please help me figure out how they got the answer:
The number of minutes between trucks arriving at a checking station are shown to follow an exponential distribution, with an average of fifty minutes between trucks arriving. The administrators of the station are concerned about congestion. It requests information on the probability that at least twenty minutes will occur between truck arrivals. You calculate this to be:
and the answer is .67
and i keep trying to get the answer but i can't
here's my working:
and that's wrong, can someone please show me how to do this?
well i was thinking
that works but then i dont get why the and .
but yeahhh we havent done integration at all in this subject.. this question is a multiple choice question and they told us that the answer is .67
coz like for the average is 1/50 and we want 20 minutes right, so i divided the 1 by 2.5 (50/20 = 2.5) so i thought and x = 20
Here's a formula you were probably given maybe:
This always yields the right tail tail of the distribution - which is what you want since youre calculating x>20..
So, the value of is 1 per 50 minutes so 1/50 = 0.02 per minute. The question is to determine the probability of there being at least 20 minutes between truck arrivals, so: