Answer:
The standard deviation of the sample mean is
Explanation:
From the question we are told that
The mean is
![\= x = 60](https://img.qammunity.org/2021/formulas/mathematics/college/f8lvo7mt11bxk8tgq4govtage4rafjevho.png)
The standard deviation is
![\sigma = 21](https://img.qammunity.org/2021/formulas/mathematics/college/7owpmiucz87iugdaqjk6z69a1cwxv38l5e.png)
The sample size is
![n = 60](https://img.qammunity.org/2021/formulas/mathematics/college/g8oolc2wlcppib7a85pia35lddqf43ihoo.png)
Generally the standard deviation of the sample mean is mathematically represented as
![\sigma _ {\= x } = (\sigma )/(√(n) )](https://img.qammunity.org/2021/formulas/mathematics/college/anm9zfan38glquw26rquqwalr92wz9axim.png)
substituting values
![\sigma _ {\= x } = ( 21 )/(√(60) )](https://img.qammunity.org/2021/formulas/mathematics/college/srtg74b6l2u1qiybbo9g3sm33mdg9ywv1m.png)
![\sigma _ {\= x } = 2.711](https://img.qammunity.org/2021/formulas/mathematics/college/2tda17kxogq6n3m776pu2pq156ucccg3cb.png)