The proportion of defective corks produced by this machine through z test comes out is 0.320.
Given mean of 2 cm and standard deviation of 0.1 cm, The diameter is between 1.9 and 2.1 cm.
We have to find the proportion of defective corks that are produced by machine.
In this problem we have to first find z score and then we will be able to find the probability of defective corks produced by the machine.
Z=(X-μ)/σ
μ=2 cm and σ=0.1 cm.
Z value corresponding to X=1.9.
Z=(1.9-2)/0.1
=-0.1/0.1
=-1
Z value corresponding to X=2.1.
Z=(2.1-2)/0.1
=0.1/0.1
=1
P value of P(-1<Z<1)=2*0.3410=0.6820
Proportion of corks which are not defective=0.6820.
Proportion of corks which are defective=1-0.680.
=0.320
Hence the proportion of defective corks produced by machine is 0.320.
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