For example
Now, use the table of the standardised normal distribution .
The life-time of a popular computer flatscreen is known to follow a normal distribution with a mean μ = 2000 hours and standard deviation σ = 200 hours. If a computer flatscreen is selected at random, find the probability that it will last for:
Less than 2500 hours.
More than 1900 hours.
Between 2000 and 2400 hours.
need a head start
can someone guide me tru this problem
This is clearly wrong. You should know that Pr(Z < 0) = 0.5, so obviously Pr(Z < 2.5) must be greater than 0.5. You need to get one-on-one help from your instructor on how to use the tables you are using. It is the same sort of question as the ones you posted here: http://www.mathhelpforum.com/math-he...on-176941.html.
You are asking the same sort of questions every time in all your threads and getting given the same help. It is time you went back and reviewed the examples in your textbook and class notes and got one-on-one help in person from someone (eg. your instructor).
Thread closed.