There are two machines available for cutting corks intended for use in bottles.
ID: 2933065 • Letter: T
Question
There are two machines available for cutting corks intended for use in bottles. The first produces corks with diameters that are normally distributed with mean 3 cm and standard deviation 0.1 cm. The second machine produces corks with diameters that have a normal distribution with mean 3.04 cm and standard deviation 0.02 cm. Acceptable corks have diameters between 2.9 cm and 3.1 cm. Which machine is more likely to produce an acceptable cork? What should the acceptable range for cork diameters be (from 3-d cm to 3 + d cm) to be 90% certain for the first machine to produce an acceptable cork?Explanation / Answer
1)for first machine:
probability of acceptable cork =P(2.9<X<3.1)=P((2.9-3)/0.1<Z<(3.1-3)/0.1)=P(1<Z<-1)=0.8413-0.1587=0.6827
2)for first machine:
probability of acceptable cork =P(2.9<X<3.1)=P((2.9-3.04)/0.02<Z<(3.1-3.04)/0.02)=P(-7<Z<3)=0.9987-0=0.9987
therefore second machine has higher probbaility of producing an acceptable work
2)
for 90% CI ; z =1.6449
hence acceptable cork diameters =mean -/+ z*std error =3-/+ 1.6449*0.1 =2.84 to 3.16