Question

The mean inside diameter of a sample of 200 washers produced by a machine is 0.502cm and the s.D is 0.005cm . The purpose for which these washers are intended allows a minimum tolerance in the diameter 0.496 cm to 0.508 cm, otherwise the washers are considered defective. Determine the percentage of defective washers produced by the machine assume the diameters are normally distributed.

Answer 1

Answer:

0% Defective Washers

Step-by-step explanation:

Mean diameter of 200 Washers = 0.502 cm

Standard deviation S.D = 0.005 cm

The diameters are normally distributed.

∴ We can find the maximum diameter of the washer as

Max Dia of the washer = Mean dia of washers + Standard deviation

∴ Dmax = 0.502 + 0.005

∴ Dmax = 0.507 cm ..... (1)

Minimum diameter of the washerin the lot can be calculated by

Min dia of washer = Mean dia of the lot - Standard Deviation

∴ Dmin = 0.502 - 0.005

∴ Dmin = 0.497   ....(2)

Tolerances of in the diameter of the washer is given as

0.496 cm to 0.508 cm

From (1) & (2)... we see that, Dmin and Dmax both lies between the tolerence limits.

∴ No defective washers will be produced by the machine.