Question

For a Normal distribution with mean, mu=2, and standard deviation, sigma = 4,

70% of all observations have values between x and y . (Round to 4 decimal places.)

Answer 1

Consult your standard Z table. 35% of all observations occur between 0 and 1.04σ. So, 70% occur between -1.04σ and 1.04σ.

So, that means that the actual values occur in
2-1.04(4) <= x <= 2+1.04(4)
-2.16 <= x <= 6.16