Answer:
Mean of the binomial distribution
μ = 174.972 bolts
Explanation:
Step(i):-
Given that Bob tested 24 bolts that he randomly picked and found that 5 were defective
The proportion of the defective item

Step(ii):-
Let 'x' be a random variable in a binomial distribution
Mean of the binomial distribution
μ = np
μ = 840 ×0.280
μ = 174.972
Final answer:-
Mean of the binomial distribution μ = 174.972 bolts