Answer:
48.514%
Explanation:
The formula for calculating a z-score is is z = (x -μ)/σ,
where x is the raw score = 149.75
μ is the sample mean = population mean = 151 seconds
σ is the sample standard deviation
= Population standard deviation/√n
Where n = 20 songs
Population standard deviation = 30
Hence, sample standard deviation
30/√20
= 6.7082039325
z = (x -μ)/σ
z = 149.75 - 150/6.7082039325
z = -0.03727
Using the z score table to find the probability, we have :
P(x<149.75) = 0.48514
In percent = 0.48514 × 100
= 48.514%
Therefore, the probability (as percent) that a random selection of 20 songs will have mean length of less than 149.75 seconds is 48.514%