Quick Normal Distribution Question [+rep]

Hi,

I've got normal distribution, mean=1, variance=16 and trying to find P(X>-1.04). I've looked up what it should be by using online normal distribution calculators but keep getting the wrong answers. Can anyone help? +rep for help :smile:

Thank you!

Reply 1

sweetfloss

15

Have you double checked you're using the right table?
Sounds daft, but a lot of the time when I got it wrong it's because the table was for values above instead of below etc.
Also - are you just using the variance value? Standard deviation is the square root of variance.

Reply 2

GingerApple

OP

Original post by sweetfloss

Have you double checked you're using the right table?
Sounds daft, but a lot of the time when I got it wrong it's because the table was for values above instead of below etc.
Also - are you just using the variance value? Standard deviation is the square root of variance.

Thanks, I've been manipulating it to suit the particular table I'm using, and I am using the sd rather than the variance. Since you're 4th year maths, do I need to standardise before applying rules of symmetry or can I manipulate first and then standardise? My impression is it doesn't make a difference but I was only taught it 24 hours ago..

Reply 3

sweetfloss

15

Original post by GingerApple

Thanks, I've been manipulating it to suit the particular table I'm using, and I am using the sd rather than the variance. Since you're 4th year maths, do I need to standardise before applying rules of symmetry or can I manipulate first and then standardise? My impression is it doesn't make a difference but I was only taught it 24 hours ago..