Status: Waiting for your answer. Formula: Given: There are 7 grams of Mendelevium-257.Mendelevium-257 has a half-life of 5.5 hours. Find: Use the formula above to calculate the time it would take for the given mass to degrade down to 0.25 grams. Calculate the solution for 't' to the nearest tenth using logarithms. Solution: t = hours