Question 1148632
The middle 40% are where the probability is 0.2000 to the left and to the right of the midline. Want the z values for both of them, which are additive inverses of each other.
this is z=-0.5244 and +0.5244
z=(x-mean)/sd
0.524=(x-64)/2.3
1.2061=x-64
x=65.2061 and also 62.7939

You did it properly--it is a matter of rounding, and 4 decimal places is not appropriate given the numbers they gave you. I would probably try doing it with rounding to 5 decimal places throughout and then round at the end.  Normally, the z is rounded to two decimal places, rarely three, and the probability to four.