I am a bit stuck on how to find the standard deviation of this question. I know the formula u need to use: x-(x bar) / Z .. But I dont know how to find the Z score!
Could you please help me with (1) find the Z score value and (2) getting to the answer...
The question being:
Monica walks to work from home and she uses route a or route b.
Her journey time, Y minutes by route B may be assumed to be normally distributed with a mean of 40 and an unknown standard deviation.
Given that P(Y > 45) = 0.12, calculate the standard deviation value.
I would really appreciate some helpful feedback and solutions!
Thanks in advance