how do i find the percentage and probability of this statistics question???
Determine.
a.) the percentage of films that last 2 hours or more.
b.) the probability that a particular film lasted 2 hours or more.
Favorite Answer
µ = Mean = 106 min.
σ = Standard Deviation = 8 min.
xbar = 120 min. (2 hours)
……………………
a) Determine the percentage of films that lasted over 2 hours.
z = (xbar – µ) / σ
z = (120 – 106) / 8
z = 14 / 8
z = 1.75
The z-value for 1.75 is 0.4599 (table look up)
The table should be in the appendix of your stats book.
If not, you can view it here:
http://rvgs.k12.va.us/statman/Table-A3.jpg
The probability that a particular film lasted more than 2 hrs.
= 0.5 – 0.4599 = 0.0401
The percentage of films lasting more than 2 hours.
= (0.5 – 0.4599) * 100 = 4.01%
Good luck in your studies,
~ Mitch ~
P.S. – If you have a TI-83 or TI-84,
you can compute this directly on your calculator:
http://www.stat.wmich.edu/s216/book/node49.html
This is a really neat way to save time on tests!
