We are given 0.3770. Since the number is behind 0 on the normal distribution curve, we can infer that 50% of data lies between the left side of the curve to the middle.
Subtracting 0.377 from 0.5, we get 0.123. Looking at our z-scores table (Table A Standard normal probabilities from AP Stats), we can see that -1.16 is closest to our desired value at 0.1230. Thus, z should be -1.16.
