Let X be normal with mean 50 and variance 9. Determine c such that P(50-c

Question

Let X be normal with mean 50 and variance 9. Determine c such that P(50-c<X<50+c)=50%

I have found sigma=3
I hope that someone can help me with the rest!
Thanks ind advance!

amistre64 · Answer

how do you determine a z score?

mathmale · Answer

We need to find c such that  P(50-c<X<50+c)=0.5.  This means that the area under the standard normal curve, from 50-c to 50+c, is 0.5.  How would you go about  finding the z scores (one negative, one of the same magnitue, but positive) that define an area under the standard normal curve that has area 0.5?

mathmale · Answer

Please type in the formula for "z-score."

sro03 · Answer

the score for 50% isn't it 0 ?

amistre64 · Answer

a zscore relates the probability that some random variable X is a given distance from the mean using the standard deviation as its unit of measure.

in order for the interval (50-c) to (50+c), to encompass 50% of the data points ... then (50-c)/sigma would have to have a z score related to 25% from the mean.

amistre64 · Answer

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