Answer
(a) $C_n=1.1C_{n-1}=(1.1)^n C_0$
(b) $7.09$ g/L
Work Step by Step
(a) Step 1. The initial concentration is $C_0=4$ g/L,
Step 2. With an increase of $10\%$, the concentration of the first day is $C_1=1.1C_0$,
Step 3. Similarly, the concentration of the second day is given by $C_2=1.1C_1$ ... ...
Step 4. The concentration of the $n$th day is then given by $C_n=1.1C_{n-1}=(1.1)^n C_0$
(b) After 8 days, let $n=8$, we have $C_8=1.1C_7= ... =7.09$ g/L as shown in the figure where the concentrations up to 12 days are calculated.
