### Home > A2C > Chapter 7 > Lesson 7.2.2 > Problem 7-119

7-119.

Substitute *n* = 1, 2, 3 into the formula.

Let *t*(*n*) = 312,500 and solve for *n*. Be sure to divide both sides of the equation by 4 before taking the log of both sides.

What kinds of numbers will tell you if it is in the sequence?

See part (b).