Final answer:
The student's question contains an apparent typo, and a corrected version of the decay function would be needed to provide the daily decay factor for einsteinium-253. Without the correct function, it is not possible to determine the exact daily change in mass, but the concept is based on the radioactive decay equation that describes how isotopes like U-238 decay over time.
Step-by-step explanation:
The question appears to have a typo in the expression for Mweek(t). Assuming the intended function for the decay of einsteinium-253 is exponential (which is a standard way to model radioactive decay), a typo-corrected version of the function might look like Mweek(t) = 15 × e^(-0.79t), where t is the time in weeks. To find the daily rate of change, we would need to know the decay constant in terms of days instead of weeks. Assuming a decay constant per day and that the equation in proper form is Mday(t) = 15 × e^(-kt), you can find the daily decay factor by evaluating e^(-k) where k is the decay constant per day.
To get an exact daily decay factor, more information or the correct functional form is needed. However, the concept of radioactive decay can be explained with the provided information that concerns radioactive substances like U-238 that have a very low decay rate and thus remain largely unchanged over human timescales, as opposed to substances that decay at a faster rate and have detectable changes in mass or activity over a shorter period. This reflects how the daily decay rate (or the decay constant) dictates the rate of mass loss over time. In higher-level physics or chemistry, this rate can be calculated using formulas derived from the radioactive decay equation.