An athletic track 14m wide consists of two straight sections 130m long joining semicircular ends whose inner radius in 3.5m. The area of the shaded region is:

\[=\frac{4}{3}\pi \times \frac{x}{4\pi }\sqrt{\frac{x}{4\pi }}=\frac{x}{3}\sqrt{\frac{x}{4\pi }.}\]

\[=\frac{4}{3}\pi {{r}^{3}}=\frac{4}{3}\pi \times {{\left( \frac{x}{4\pi } \right)}^{3/2}}\]

\[\frac{\frac{4}{3}\pi {{r}^{3}}}{\frac{4}{3}\pi {{(21-r)}^{3}}}=\frac{64}{27}\]

An athletic track 14m wide consists of two straight sections 130m long

1.	An athletic track 14m wide consists of two straight sections 130m long joining semicircular ends whose inner radius in 3.5m. The area of the shaded region is:
A.	\[=\frac{4}{3}\pi {{r}^{3}}=\frac{4}{3}\pi \times {{\left( \frac{x}{4\pi } \right)}^{3/2}}\]
B.	\[=\frac{4}{3}\pi \times \frac{x}{4\pi }\sqrt{\frac{x}{4\pi }}=\frac{x}{3}\sqrt{\frac{x}{4\pi }.}\]
C.	\[\frac{\frac{4}{3}\pi {{r}^{3}}}{\frac{4}{3}\pi {{(21-r)}^{3}}}=\frac{64}{27}\]
D.	None of these
Answer» B. \[=\frac{4}{3}\pi \times \frac{x}{4\pi }\sqrt{\frac{x}{4\pi }}=\frac{x}{3}\sqrt{\frac{x}{4\pi }.}\]