The area of a triangle is given by the formula

, where B is the base and h is the height. We can rearrange this formula to solve for B.

.
We plug in the given area, 640 square millimeters, and the given height, 32 millimeters.

.
40 mm is our final answer.
Answer:
B
Step-by-step explanation:
Initial mean = 156, Changed mean = 163.92
So, mean increases. Only condition that satisfies this is B.
Yeah I know why ?????,????