1. Culture A.
Since the number of cells increases by 200 each day and every day thereafter, then after seven days the number of cells will increase by
![200\cdot 7=1,400.](https://img.qammunity.org/2019/formulas/mathematics/high-school/38jt5089tmamu5vwombvfax2pt61pm33f7.png)
2. Culture B.
The initial number of cells was 1,000. Since the number of cells increases 8% each day and every day thereafter, then after seven days the number of cells will be
![1,000\cdot (1.08)^7\approx 1,713.](https://img.qammunity.org/2019/formulas/mathematics/high-school/qoxrttvljqsu1d10dju4vgsyrmmbsss41k.png)
The number of cells that have grown by the end of the seventh day is
1,713-1,000=713.
Answer: option A -- Culture A: 1400 cells Culture B: 713 cells