Question

An element with mass 670 grams decays by 21.8% per minute. How much of the element is remaining after 15 minutes, to the nearest 10th of a gram?

Answer 1

Answer: 16.8

im doing the delta math

Answer 2

`16.76\ g`

Explanation:

In this problem we have a exponential function of the form

`y=a(b^x)`

where

x is the time in minutes

y is the mass of the element in grams

a is the initial value or y-intercept

b is the base

r is the rate

b=(1+r)

we have

`a=670\ g`

`r=-21.8\%=-21.8/100=-0.218`

`b=1-0.218=0.782`

substitute

`y=670(0.782^x)`

so

For x=15 min

substitute in the exponential equation

`y=670(0.782^15)`

`y=16.76\ g`