A normal distribution means that mean = median = mode. Furthermore, in a normal distribution, 68% of values are within 1 standard deviation of the mean, 95% of values are within 2 standard deviations, and 99.7% are within 3 standard deviation.
The mean is 150 and the standard deviation is 15. 165 and 135 1 standard deviation away from the mean, so 68% of values are between 135 and 165. This means that 32% of values are not between those values. A normal distributuion is symmetric, so 16% of values are greater than 1 standard distribution and 16% are less. Therefore, 16% of values (160) are less than 135 and 16% of values (160) are greater than 165
