Answer:
-2.8
Step-by-step explanation:
Given that:
Mean, μ = 78
Standard deviation, σ = 5
Omar's score, x = 64
The Zscore of Omar's score :
Zscore = (x - μ) ÷ σ
Zscore = (64 - 78) / 5
Zscore = - 14 / 5
Zscore = - 2.8
Hence, Omar's exam score is - 2.8