The formula for calculating z score is expressed as
z = (x - μ)/σ
where
x represents sample mean
μ represents population mean
σ represents population standard deviation
From the information given,
x = 55
μ = 98
σ = 5
By substituting these values into the formula,
z = (55 - 98)/5 = - 43/5
z = - 8.6
