Stats Question

[Tamooma]

The mean is μ=15.2 and the standard deviation σ=0.9 . Find the probability that χ is greater than 15.2

[mac44]

0.5000

[Jackdaw33]

I'd love to know how you worked that out.

[fiction-factory]

What distribution you are using (probably normal) and the confidence level?
Which quiz is this?
How confident are you that mac is right?
I think the value of σ is a red herring here

[fiction-factory]

Jackdaw- I think mac is simply saying that if it's a balanced distribution (like the normal bell curve or a uniform distribution then half the values will be above the mean and half below the mean (give or take some that are exactly on the mean)

[Fibonacci]

It's very confusing when the odds are evens! :-)

[fiction-factory]

I thought the question seemed odd.
I think the question should be:

Assume that X has a normal distribution, and find the indicated probability.
The mean is µ= 15.2 and the standard deviation is σ = 0.9.
Find the probability that X is greater than 16.1.

http://www.compton.edu/facultystaff/jmmartinez/docs/Math-150-Spring-2015/Math-150-E3-SP15-Practice.PDF

[Baldric]

http://www.talkstats.com/showthread.php/15298-Indicated-probability

[fiction-factory]

Maybe the question was right. Variations on this question seem common on US exam papers.
Here's the same Q that Tamooma asked

59) The mean is μ = 15.2 and the standard deviation is σ = 0.9.
Find the probability that X is greater than 15.2.

A) 0.5000 B) 1.0000 C) 0.9998 D) 0.0003

The answer was indeed A} 0.5

http://www.brazosport.edu/faculty-staff/directory/CalinAgut/Documents/Practice%20PDF%20Statistics/Review%202,%20Stat%20(OK).pdf

[Baldric]

Jackdaw

Normal distribution is symmetric; its mean \mu = median.
Hence we have \Pr\{X < \mu\} = \Pr\{X > \mu\} = 0.5

See 16:38