The z-score can be calculated by the following formula:
![z=(x-m)/(\sigma)](https://img.qammunity.org/2023/formulas/mathematics/college/9dv01d9ah8i3ijc4nd0w6mi4ejcemg1vfd.png)
Where m is the mean, σ is the standard deviation and x is the actual score.
By replacing John's result (83) for x, 79 for m and 3.5 for σ, we get:
![z=(83-79)/(3.5)=1.14](https://img.qammunity.org/2023/formulas/mathematics/college/f5da78licdlhw671o3gbr9hd7kkt3fsbuo.png)
Similarly, for Jane's result on test B:
![z=(80-77)/(2.5)=1.2](https://img.qammunity.org/2023/formulas/mathematics/college/upqnlx3onczv5dff9uro0a7jj4zhqlxia2.png)
John's z-score was 1.14 and Jane's z-score was 1.2, then, Jane did better than John