Solve the Problem $\mathrm { y } = 16 \mathrm { t } ^ { 2 } \mathrm { ft }$

Multiple Choice

Solve the problem.
-Assume that a watermelon dropped from a tall building falls $\mathrm { y } = 16 \mathrm { t } ^ { 2 } \mathrm { ft }$ in $\mathrm { t }$ sec. Find the watermelon's average speed during the first $4 \mathrm { sec }$ of fall and the speed at the instant $t = 4 \mathrm { sec }$ .

A) $32 \mathrm { ft } / \mathrm { sec } ; 64 \mathrm { ft } / \mathrm { sec }$
B) $128 \mathrm { ft } / \mathrm { sec } ; 65 \mathrm { ft } / \mathrm { sec }$
C) $64 \mathrm { ft } / \mathrm { sec } ; 128 \mathrm { ft } / \mathrm { sec }$
D) $65 \mathrm { ft } / \mathrm { sec } ; 130 \mathrm { ft } / \mathrm { sec }$