The chemical element einsteinium-$253$ naturally loses its mass over time. The relationship between the elapsed time $t$, in weeks, since a sample of einsteinium was measured, and its mass, $M(t)$, in grams, is modeled by the following function: ###$M(t)= \left(0.97\right)\^{\Large 7t+5}$ **Complete the following sentence about the weekly rate of change in the mass of the sample.** *Round your answer to two decimal places.* Every week, the mass of the sample is multiplied by a factor of [[☃ numeric-input 1]].