To find the z-score for a given systolic blood pressure reading, we need to use the z-score formula:
z = (x - mu) / sigma
where z is the z-score, x is the raw score, mu is the mean, and sigma is the standard deviation.
In this case, we are given that mu = 121 and sigma = 15. We can use this information to find the z-score for each of the given blood pressure readings:
A. For a blood pressure reading of 142, we have:
z = (142 - 121) / 15
= 21 / 15
= 1.4
Therefore, the z-score for a blood pressure reading of 142 is approximately 1.4, to the nearest tenth.
B. For a blood pressure reading of 130, we have:
z = (130 - 121) / 15
= 9 / 15
= 0.6
Therefore, the z-score for a blood pressure reading of 130 is approximately 0.6, to the nearest tenth.
C. For a blood pressure reading of 103, we have:
z = (103 - 121) / 15
= -18 / 15
= -1.2
Therefore, the z-score for a blood pressure reading of 103 is approximately -1.2, to the nearest tenth.