Answer:
52.63% probability that thids intial repair was made by the first technican
Explanation:
Bayes Theorem:
Two events, A and B.

In which P(B|A) is the probability of B happening when A has happened and P(A|B) is the probability of A happening when B has happened.
In this question:
Event A: Incomplete repair
Event B: Made by the first technican.
The first technican, who services 40% of the breakdowns, has 5% chance of making incomplete repair.
This means that
.
Probability of an incomplete repair:
5% of 40%(first technican) or 3% of 60%(second technican). So

Given that there is a problem with the production line due to an incomplete repair, what is the probability that thids intial repair was made by the first technican

52.63% probability that thids intial repair was made by the first technican