# Thread: Time Sample Space and Event

1. ## Time Sample Space and Event

A telephone call from a certain person is received some time between 7:00 A.M. and 9:10 A.M. every day. Define a sample space for this phenomenon, and describe the event that the call arrives within 15 minutes of the hour.

The sample space is straight forward S = {[7, 55/6]}, but the event is confusing me. Can anyone suggest a solution?

2. ## Re: Time Sample Space and Event

Originally Posted by joshuaa
A telephone call from a certain person is received some time between 7:00 A.M. and 9:10 A.M. every day. Define a sample space for this phenomenon, and describe the event that the call arrives within 15 minutes of the hour. The sample space is straight forward S = {[7, 55/6]}, but the event is confusing me. Can anyone suggest a solution?
I am confused by the term the hour.
From $7 \text{ to }9:10$ is $130$ minuets.
Do you know if that means 7am, 8am, or 9am? Or just one of those.
If could mean $[7,7:15]\cup[7:45,8:15]\cup [8:45,9:10]$ But the wording is not clear.

3. ## Re: Time Sample Space and Event

i think your approach is correct, but why you did not choose [7:15, 7:30]?

i don’t understand why you choose [8:45, 9:10], isn’t that only within 10 minutes of the 9 hour, not within 15 minutes!!

4. ## Re: Time Sample Space and Event

[7:15,7:30] is not within 15 min of the hour.

Because you are told that the call takes place between 7:00 and 9:10, the period between 9:10 and 9:15 is not included.

5. ## Re: Time Sample Space and Event

Originally Posted by joshuaa
i think your approach is correct, but why you did not choose [7:15, 7:30]?
i don’t understand why you choose [8:45, 9:10], isn’t that only within 10 minutes of the 9 hour, not within 15 minutes!!
Well it is my reading of the phrase "The Hour". I take that to mean calls come in around 15 min. of the hour change.
Within 15 min of seven; within 15 min of eight; or within 15 min of nine.
The question specifies that call come in "between 7:00 A.M. and 9:10 A.M."
Thus from $\displaystyle [7,7:15]$ around 7, $\displaystyle [7:45,8:15]$ around 8, & $\displaystyle [8:45,9:10]$ around 9.

6. ## Re: Time Sample Space and Event

thanks guys. that's clear.