You need to use the equation that relates the raw score and the z score such that:
`z = (x - mu)/sigma`
x represents the raw score, `sigma` represents the standard deviation and `mu` is the mean.
Notice that the problem gives only the value of z score, hence, you should substitute this value in the equation above such that:
`2.5 = (x - mu)/sigma =gt 2.5 sigma = x - mu`
You need to isolate the raw score such that:
`x = mu + 2.5 sigma`
Hence, evaluating the raw score if only the z score is given yields `x = mu + 2.5 sigma` .