Question

TThe probability that an observation, following a normal distribution, will lie within μ ± 1.3σ is
a. 9.5 %
b. 19.0%
c. 40.3%
d. 50.0%
e. 80.6%

Answer 1

You can do all kinds of fun Z table stuff at

http://davidmlane.com/hyperstat/z_table.html