Answer:
b
Step-by-step explanation:
Start from the right-most 7, and go one digit to the left each time:
7 - units place
7 - tens place
7 - hundreds place
3 - thousands place
2 - ten-thousands place
6 - hundred-thousands place
5 - millions place
4 - ten-millions place <----- answer to this question
1 - hundred-millions place
8 - billions place
0 - ten-billions place
9 - hundred billions place
The ten-millions place is the 4.
The area of an equilateral triangle of side "s" is s^2*sqrt(3)/4. So the volume of the slices in your problem is
(x - x^2)^2 * sqrt(3)/4.
Integrating from x = 0 to x = 1, we have
[(1/3)x^3 - (1/2)x^4 + (1/5)x^5]*sqrt(3)/4
= (1/30)*sqrt(3)/4 = sqrt(3)/120 = about 0.0144.
Since this seems quite small, it makes sense to ask what the base area might be...integral from 0 to 1 of (x - x^2) dx = (1/2) - (1/3) = 1/6. Yes, OK, the max height of the triangles occurs where x - x^2 = 1/4, and most of the triangles are quite a bit shorter...
