The formula for calculating the z score is expressed as
z = (x - μ)/σ
We want to find mean, μ
From the information given,
z = 2.25
x = 14.6
σ = 3.6
Thus,
2.25 = (14.6 - μ)/3.6
Cross multiply
(14.6 - μ) = 2.25 * 3.6
14.6 - μ = 8.1
μ = 14.6 - 8.1
μ = 6.5