Question

An element with mass 970 grams decays by 27.7% per minute. How much of the element is remaining after 13 minutes, to the nearest 10th of a gram?

Answer 1

Every 1 minute, you multiply the mass by 27.7% or 0.277

after 1 minute, you multiply once
after 2 minutes, you multiply twice
3, thrice
etc
so after 13 minutes, you multiply 13 times or 0.277^13

so what is 970g *0.277^13 =?

Answer 2

970×(1−0.277)^(13)
=14.3