This paper explores the critical role of work study and line balancing in optimizing productivity within mass production assembly lines, where multiple operators execute tasks across a sequence of stations. Work study is fundamental for estimating task times, analyzing work methods, and improving productivity while minimizing waste. Line balancing ensures a smooth, uninterrupted production flow, mitigating bottlenecks and optimizing resource utilization. This paper applies the Maynard Operation Sequence Technique (MOST) to estimate standard process times, facilitating effective work allocation to operators. Focusing on the automotive industry's multi-model assembly line method, this study addresses the complexities of multiple operators at the same workstation. Considering the automotive industry's layout, processes, and supply constraints, the paper proposes a constrained programming model to optimize workload allocation and maximize operator utilization. With takt time, the number of stations, operators, and processes set as parameters in each iteration, the results demonstrate the optimal allocation of operators to stations and the total manpower required in the assembly shop to meet customer demand.