Question

The scores of students had a normal distribution with μ=548.6 and σ=28.4 (a) What's the prob. that a student's test scores 555 or higher?

Answer 1

Standard score: z = (x - μ)/σ = (555 - 548.6) / 28.4 = 0.225

 

Now standard normal table to find Φ(0.225) = 0.589

 

P(x<555)=0.589

 

Calculate probability that a student's test scores 555 or higher.

 

P(x≥555) =1-P(x<555)=1-0.589 =0.411