Answer:
Z = -1.2 ( It is below the group mean), The sudent performed less than average.
Step-by-step explanation:
From the question,
Applying
Z = (x-μ)/σ........................ Equation 1
Where Z = z-score, x = observed score or raw score, μ = mean of the score, σ = standard deviation of the score
Given: x = 55 marks, μ = 70, σ = 12
Substitute these values into equation 1
Z = (55-70)/12
Z = -15/12
Z = -1.25
Hence the z- score is negative, meaning it is below the group mean, I.e the student who get 55 marks, performed less than average
