$($a$)$ list and explain the different stages followed in new product or service design process

$($b$)$ mr shiv kumar a air conditioner repairing person is called for ac repairing and service purpose $.$ although he has received extensive training $,$ he also relies heavily on his equipments for support $.$ during a normal call $,$ he uses five essential equipments $,$ which reliabilities are $0\mathrm{.}98,0\mathrm{.}97,0\mathrm{.}95$ and $0\mathrm{.}99,$ respectively $.$