Answer:
a) the required probability is 0.0013
b) the required probability is 0.0288
c) the required probability is 0.9759
Step-by-step explanation:
Given the data in the question;
let x be the thickness measurements
Given that X follows a Normal distribution with mean μ = 5.4
standard deviation σ = 0.8
then z = x-μ / σ = x-5.4 / 0.8 follows standard Normal
a) probability that the thickness is less than 3.0 mm
P( x<3 ) = P( x-5.4 / 0.8 < 3-5.4 / 0.8 ) = P( Z < -3.00 ) = 0.0013
Therefore, the required probability is 0.0013
b) the thickness is more than 7.0 mm
P( x>7 ) = P( x-5.4 / 0.8 > 7-5.4 / 0.8 ) = P( Z > 2.00)
= 1 - P( Z ≤ 2)
= 1 - 0.9772
= 0.0288
Therefore, the required probability is 0.0288
c) the thickness is between 3.0 mm and 7.0 mm
P(3< x<7 ) = P( x<7) - P(x<3)
= P( x-5.4 / 0.8 > 7-5.4 / 0.8 ) - P( x-5.4 / 0.8 < 3-5.4 / 0.8 )
= P( Z< 2 ) - P( Z < -3)
= 0.9772 - 0.0013
= 0.9759
Therefore, the required probability is 0.9759
