you should transform J into standard normal distribution variable before solving the equation for
which is
J∼N(108,σ2)Jam is sold in jars and the mean weight of the contents is 108 grams. Only 3% of jars have contents weighing less than 100 grams. Assuming that the weight of jam in a jar is normally distributed find
a the standard deviation of the weight of jam in a jar,
b the proportion of jars where the contents weigh more than 115 grams.
a)
From here do I not just look up the z value for 0.03 in the 'z tables'? In the book it gives z = -1.88? I dont know how they got this number. Can anyone explain?
I thought the equation should be
0.5120 is the value in the 'z'' tables that corresponds to 0.03.
but the correct equation to solve for the standard deviation is
Thanks.