Answer
given,
X = 40 z = +1.00,
X = 28 z = -0.50
[tex]Z = \dfrac{x - \mu}{\sigma}[/tex]
[tex]1 = \dfrac{40 - \mu}{\sigma}[/tex]
[tex]\sigma =40 - \mu[/tex] ..................(1)
[tex]-0.5 = \dfrac{28 - \mu}{\sigma}[/tex]
[tex]-0.5\sigma =28 - \mu[/tex]...............(2)
from equation (1) and (2)
[tex]1.5\sigma = 12[/tex]
[tex]\sigma = 8[/tex]
from equation (1)
[tex]8 =40 - \mu[/tex]
[tex]\mu = 32[/tex]
