Question

Computer keyboard failures are due to faulty electrical connects (8%) or mechanical defects (92%). Mechanical defects are related to loose keys (27%) or improper assembly (73%). Electrical connect defects are caused by defective wires (35%), improper connections (13%), or poorly welded wires (52%). Round your answers to four decimal places (e.g. 98.7654).

Answer 1

Faulty electrical connects = P(A) = 0.80

Mechanical defects = P(B) = 0.92

Mechanical defects are related to loose keys = P(C/B) = 0.27

Improper assembly = P(D/B) = 0.73

Defective wires = P(E/A) = 0.35

Improper connections = P(F/A) = 0.13

Poorly welded wires = P(G/A) = 0.52

Now, the probability due to loose keys = 0.27 x 0.92 = 0.2484

Improperly connected = 0.13 x 0.80 = 0.1040

Poorly welded wires = 0.52 x 0.80 = 0.4160

So, the probability that a failure is due to improperly connected or poorly welded wires = 0.1040 + 0.4160

= 0.5200