...of the area under the curve lies to the left of the line? Assuming this is what the question is asking for, the z score of 0, the mean, is a vertical line which equally divides the area under the distribution curve corresponds to 50% or 0.5. So 47.5% is a little to the left of z=0, so z<0. Therefore, we need to know the value of z 2.5% below the mean. The table gives z=-0.0628 approx. by extrapolation. This means that a data value is 0.0628 standard deviations below the mean. The area to the left of the line represents the cumulative probability (47.5%) of scores below the data value, the proportion of data in the distribution lying at or below the data value.