There are presently $N = 300$ cases of Bangkok flu, and the number is growing by 40 new cases every month. Rewrite the rate in mathematical notation.
A) $\frac { \mathrm { d } N } { \mathrm {~d} t } = \frac { 2 } { 15 }$
B) $\frac { \mathrm { d } N } { \mathrm {~d} t } = 40$
C) $\mathrm { d } N = 40$
D) $\frac { \mathrm { d } N } { \mathrm {~d} t } = 7.50$
E) $N = 40$

Question

There are presently $N = 300$ cases of Bangkok flu, and the number is growing by 40 new cases every month. Rewrite the rate in mathematical notation.  
A) $\frac { \mathrm { d } N } { \mathrm {~d} t } = \frac { 2 } { 15 }$
B)   $\frac { \mathrm { d } N } { \mathrm {~d} t } = 40$
C)   $\mathrm { d } N = 40$
D)   $\frac { \mathrm { d } N } { \mathrm {~d} t } = 7.50$
E)  $N = 40$

Quizplus · Accepted Answer

The rate of change of the number of cases, $N$, with respect to time, $t$, is given by $\frac { \mathrm { d } N } { \mathrm {~d} t }$. Since the number of cases is increasing by 40 every month, the correct mathematical notation for the rate is $\frac { \mathrm { d } N } { \mathrm {~d} t } = 40$.

There Are Presently N=300N = 300N=300 Cases of Bangkok Flu, and the Number Is Growing by and the Number

There Are Presently $N = 300$ Cases of Bangkok Flu, and the Number Is Growing by and the Number