The probability that a randomly received emergency call is between 5 and 10 min is 77.97%.
Z score is used to determine by how many standard deviations the raw score is above or below the mean. It is given by:
z = (x - μ) / σ
Where μ is the mean, σ is the standard deviation and x is the raw score.
Given that μ = 6.4, σ = 1.7
For x = 5:
z = (5 - 6.4) / 1.7 = -0.83
For x = 10:
z = (10 - 6.4) / 1.7 = 2.12
a) P(5 < x < 10) = P(-0.83 < z < 2.12) = P(z < 2.12) - P(z < -0.83) = 0.9830 - 0.2033 = 0.7797
b) P( x < 5) = P(z < -0.83) = 0.2033
c) P(x > 10) =1 - P(z < 2.12) = 1 - 0.9830 - 0.2033 = 0.017
The probability that a randomly received emergency call is between 5 and 10 min is 77.97%.
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