Z-scores
Convert between raw scores and z-scores using z = (x - mean) / sd. Unlimited questions, five difficulty levels, and a full worked solution every time — free.
Try one
For daily screen time, the mean is 159 min with a standard deviation of 23 min. A particular value is 124.5 min. Find its z-score.
z = (x - mean) / sd
Answer: -1.5
See one solved, step by step
For sprint times in the 100 m dash, the mean is 16 s with a standard deviation of 3 s. A particular value is 19 s. Find its z-score.
z = (x - mean) / sd
📘 Worked solution
1z = (19 - 16) / 3The z-score formula is (value - mean) / standard deviation.
2= 3 / 3 = 1Subtract first, then divide.
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