## Intermediate Algebra for College Students (7th Edition)

(a.) one student started the rumor in the class. (b.) $10$ student in the class have heard the rumor after $4$ minutes.
The given formula is $N=\frac{25}{1+24\cdot 2^{-t}}$ Where, Number of people in the class $N$ who have heard the rumor after $t$ minutes. (a.) The rumor started at $t=0$. Plug above value into the formula. $N=\frac{25}{1+24\cdot 2^{-(0)}}$ $N=\frac{25}{1+24\cdot 1}$ $N=\frac{25}{1+24}$ $N=\frac{25}{25}$ $N=1$. (b.) Given value of $t$ is $4$. Plug above value into the formula. $N=\frac{25}{1+24\cdot 2^{-(4)}}$ $N=\frac{25}{1+24\cdot \frac{1}{2^4}}$ $N=\frac{25}{1+\frac{24}{16}}$ $N=\frac{25}{1+\frac{3}{2}}$ $N=\frac{25}{\frac{2+3}{2}}$ $N=\frac{25}{\frac{5}{2}}$ $N=5 \times 2$ $N=10$