The probability that the sample mean is less than 42 is 0.55567
Given,
Population mean, μ = 40
Standard deviation, σ = 100
Sample size, n = 50
Sample mean, ₓ⁻ = 42
We have to find the standard score, z =(ₓ⁻ – μ) / (σ/√n)
Substituting the values we get,
Z < (ₓ⁻ – μ) / (σ/√n)
Z < (42 – 40) / (100 / √50)
Z < (2) / (100/ 7.07)
Z < (2 / 14.44)
Z < 0.14
Using the z score table we get the corresponding z score as 0.5567
That is,
The probability that the sample mean is less than 42 is 0.55567
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