00:01
In this question, we're given a certain twitter user tweets.
00:05
At a mean rate of 9 tweets per hour, in part a, let x be the number of tweets in a given one hour period.
00:13
So x follows the poison distribution.
00:16
The mean is 9.
00:17
So probability x equals to r, where r is the number of tweets in a one hour period, will be 9 to the power of r over r factorial times e to power minus 9.
00:28
I want to find probability 7 tweets are received in a given hour.
00:33
So we're looking at probability x equals to 7.
00:36
So just sub 7 into the r.
00:43
And we have this value, which is 0 .1171 4 decimal place.
00:53
Next, in b, i'm going to let y be the number of tweets in a given 1 .25 hour period.
00:59
Since x follows the poison distribution, y will also follow the poison distribution.
01:04
The mean is 9 per hour times 1 .25 hours.
01:09
So y follows the poison distribution with the mean of 11 .25...