Question 919643
P(z) = Area under the standard normal curve <u>to the left of the particular z</u>  
Note: z = 0 (x value: the mean) 50% of the area under the curve is to the left and 50%  to the right
{{{drawing(400,200,-5,5,-.5,1.5, graph(400,200,-5,5,-.5,1.5, exp(-x^2/2)), green(line(1,0,1,exp(-1^2/2)),line(-1,0,-1,exp(-1^2/2))),green(line(2,0,2,exp(-2^2/2)),line(-2,0,-2,exp(-2^2/2))),green(line(3,0,3,exp(-3^2/2)),line(-3,0,-3,exp(-3^2/2))),green(line( 0,0, 0,exp(0^2/2))),locate(4.8,-.01,z),locate(4.8,.2,z))}}}
using the 68/95/99.7 rule (note: {{{(100-68)/2}}} = 16% 
(a) P(x&#8804;1) = 50% + 16% = 66%
(b) P(x&#8804;&#8722;1) = 16%
 (c) mean 
 (d) standard deviation 
 (e) P(x&#8805;2) = 2.5% {{{(100-95)/2 = 2.5}}}