Answer:
It will take 13.58 minutes until there are 80 grams of the element remaining
Explanation:
An element with a mass of 990 grams decays by 16.9% per minute.
We are supposed to find how long will it be until there are 80 grams of the element remaining
Formula :
![N(t)=N_0(1-r)^t](https://img.qammunity.org/2021/formulas/mathematics/college/qpi8q6es752uvs06j7n7qmna9y9xqeynz1.png)
N(t)=Amount after t minutes
=Initial amount
r = rate of decrease = 0.169
t = time in minutes
Substitute the values in the formula :
![80=990(1-0.169)^t](https://img.qammunity.org/2021/formulas/mathematics/college/ogdajvueh4sediu3a5mxuludez2bb2g9d1.png)
![(80)/(990)=0.831^t](https://img.qammunity.org/2021/formulas/mathematics/college/o008gnngr6fxgnw87b4vn9odx4jbj0yjar.png)
t=13.58
Hence It will take 13.58 minutes until there are 80 grams of the element remaining