A normal variate has mean 150 and variance 25 . Find the standard
deviation.

The standard deviation is the square root of the variance. Given a variance of 25, you simply take the square root, which is 5. So, the standard deviation of your normal variate is 5. This value tells you how spread out the data is around the mean of 150!

In real-world situations, a standard deviation of 5 in this context means that most data points will fall within 5 units above or below the mean. So if you were looking at test scores, you might find that about 68% of students scored between 145 and 155. This helps in understanding the consistency of the data!