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# Normal Distribution ASAP HELP watch

1. The random variableX~ N(μ,σ2).The lower quartile of X is 25 and the upper quartile of X is 45.Find the value of μ and the value of σ.
How do i do this type of question? I know i have to use the Z formula. But im unsure about quartiles.
2. probability of z less than 25 minus μ over sigma equals 0.25( lower quaritle is the value where the percent of data before and including it is 25 percent)
probability of z less than 45 minus μ over sigma equals 0.75
find corresponding values in normal distribution tables
solve equations simultaneously

probability of z less than 25 minus μ over sigma equals 0.25( lower quaritle is the value where the percent of data before and including it is 25 percent)
probability of z less than 45 minus μ over sigma equals 0.75
find corresponding values in normal distribution tables
solve equations simultaneously

What is the value of the mean? wouldn't it be 35
How do you know the standard deviation is 0.75??
Can you please do a step by step , im so confused
Thx alot
4. Anyone there to help me?
ASAP
WHY IS SIGMA 0.75????
5. You dont know the value of mu or sigma. But you know that the lower quartile is the value where 25 percent is less than it and the upper quartile is where 75 percent is less than it
So p (z<25-mu/sigma) equals 25 percent or 0.25
And p(z <45 -mu over sigma) equals 75 percent or 0.75
Solve simultaneously

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Updated: February 14, 2016
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