# Differential Equations : Radioactive Decay

Not what you're looking for?

The rate of decay of a radioactive substance is proportional to the amount of the substance present. Two years ago there were 5 grams of substance. Now there are 4 grams. How many grams will there be 4 years from now?

A. 16/25 B. 2 C. 64/25

D. 16/5 E. 25/4

##### Purchase this Solution

##### Solution Summary

Rate of decay is used to calculate the amount of a radioactive substance after a given time has elapsed. The solution is detailed and well presented. The response was given a rating of "5" by the student who originally posted the question.

##### Solution Preview

The answer is C.

Suppose the amount of the radioactive substance is y and the time it t years.

The rate of decay is ...

##### Purchase this Solution

##### Free BrainMass Quizzes

##### Know Your Linear Equations

Each question is a choice-summary multiple choice question that will present you with a linear equation and then make 4 statements about that equation. You must determine which of the 4 statements are true (if any) in regards to the equation.

##### Solving quadratic inequalities

This quiz test you on how well you are familiar with solving quadratic inequalities.

##### Multiplying Complex Numbers

This is a short quiz to check your understanding of multiplication of complex numbers in rectangular form.

##### Exponential Expressions

In this quiz, you will have a chance to practice basic terminology of exponential expressions and how to evaluate them.

##### Graphs and Functions

This quiz helps you easily identify a function and test your understanding of ranges, domains , function inverses and transformations.