~N(100,256) Calculating prob. below 120

[holdyourhorsiieees]

How would I calculate the probability below 120 given the mean of the normal distribution, 100, and standard deviation 16 (square root of 256)?


Thanks in advance!

 

[tkhunny]

\(\displaystyle \L\;z\;=\;\frac{120-100}{16}\;=\;1.25\)?

 

[holdyourhorsiieees]

ok, i understand that is the z score. is that the answer though also? or using the ti 83 would i do normcdf(-E99,120,100,16)?

 

[holdyourhorsiieees]

and what if i wanted to find above 120?

sorry, i forgot to put that in my initial question.

 

[tkhunny]

I think you have it correct on your TI.

If you want the other side, you need 1 - normcdf(-E99,120,100,16)

Good work.