a teacher marking an extra credit assignment gave the following marks: 49, 53, 61, 65, 68, 71, 79, 87, 88, 90
what is the z-score corresponding to the lowest mark?
Compute the mean and the standard deviation. The mean is 71.1.
You do the standard deviation. It is about 15. There are websites online that calculate it for you.
49 is 22.1 below the mean.
The z-score is -22.1/(standard deviation)