A "reasonable assumption" refers to a belief or guess that is logical and sensible based on the available information or evidence. It means making an educated guess that is likely to be true or accurate, given the circumstances. Full definition
Police forces and authorities had generally made reasonable assumptions about the financial challenge ahead, and used these to work out their budgets for the next four years. (politics.co.uk)
While we believe these expectations and projections are based on reasonable assumptions, such forward - looking statements are inherently subject to risks, uncertainties and assumptions. (cnbc.com)
Finally, it would also be interesting to see what happens if you use more reasonable assumptions. (judithcurry.com)