For the answer to the question above,
Sample mean is given by,
x = (1/n)∑x˅i .... ˅ means sub
x = (1/5)(60 + 40 + 35 + 45 + 39)
= 43.8
z-score is given by,
z = (X - μ)/σ .... μ is population mean, σ is the standard deviation
z = (43.8 - 43.8)/8.7
= 0
so the answer is zero
I hope my answer helped you.
