Now we need to find the percentage of scores that are below -1.75. To do this, we need to look -1.75 up in the normal distribution table (your teacher should have given you one or there should be one in your textbook). If we do this, we find that approximately 4% of scores are below -1.75.
z = (X - M)/S, where X is a score, M is the mean and S is the standard deviation. In your case, we have z = (1 - 2.4)/.8. This gives us a z-score of -1.75.
