Decisive set method [32]

A fuzzy approach

Modified subgradient method [32]

A fuzzy approach

Zimmermann’s extended approach [15]

An IF approach

Our proposed approach

An IF approach

x 1 = 1.1474

x 1 = 1.1475

x 1 = 1.470526

x 1 = 1.598683

x 2 = 0.7508

x 2 = 0.7514

x 2 = 0.9410526

x 2 = 1.173458

α = 0.5491

α = 0.90

β = 0.08421

β = 0.09

Z * = 4.5474

Z * = 4.5492

Z * = 5.7642098

Z * = 6.735325