Question

Two production lines produce the same parts per week of which 100 are defective. Line 2 produces 2,000 parts per week of which 150 are defective. If you choose a part randomly from the stock what is the probability it is defective? If it is defective what is the probability it part. Line 1produces 1,000 produced by line 1?

Answer 1

Answer:

(a) 0.0833 or 8.33%

(b) 0.40 or 40%

Step-by-step explanation:

Parts line one (n1) = 1,000 parts

Defects line one (d1) = 100 parts

Parts line two (n2) = 2,000 parts

Defects line two (d2) = 150 parts

Total number of parts (n) = 3,000 parts

a. Probability of a randomly selected part being defective:

$P(d) = \frac{d_1+d_2}{n_1+n_2}=\frac{100+150}{1,000+2,000}\\P(d) =0.0833=8.33\%$

The probability is 0.0833 or 8.33%

b. Probability of a part being produced by line one, given that it is defective:

$P(1|d)=\frac{P(1\cap d)}{P(1\cap d)+P(2\cap d)}\\P(1|d)=\frac{\frac{100}{3,000} }{\frac{100}{3,000}+\frac{150}{3,000}}\\P(1|d)=0.4 = 40\%$

The probability is 0.40 or 40%.