A normal distribution has mean 08 standard deviation 0078

A normal distribution has mean = 0.8, standard deviation = 0.078

1) What proportion of this distribution is lower than 0.6

2) What proportion of this distribution is higher than 0.9

Let us calculate the z-scores

Mean = 0.8

SD = 0.078

P(X < 0.6) = P ( Z < 0.6 - 0.8 / 0.078)

= P(Z < -2.564)

= 0.005172

Similarly,

P ( X > 0.9) = 1 - P (X < 0.9)

= 1 - P ( Z < 0.9-.0.8 / 0.078)

= 1 -P(Z < 1.282)

= 0.099912

Hope this helps. Ask if you have any doubts.