The mean score for a standardized test is 1700 points. The results are normally distributed with a standard deviation of 75 points. The z-score of any score x is given by `z = (x - mu)/sigma` where `mu` is the mean equal to 1700 here and `sigma` is the standard deviation equal to 75 here.
The z-score of 1800 = `(1800 - 1700)/75 = 100/75 = 4/3`
The required z-score is `4/3`