In a production process is it possible to have decreasing marginal product in an input and yet increasing returns to scale?

Yes, it is possible to have decreasing marginal product for an input while still experiencing increasing returns to scale. Decreasing marginal product occurs when adding more of a particular input results in smaller increases in output. However, increasing returns to scale implies that when all inputs are increased proportionally, the output increases by a greater proportion. This can happen if the production process benefits from efficiencies or synergies that arise from scaling up production, despite the diminishing returns on individual inputs.