The sound of thunder travels away from a lightning flash at $331 \mathrm{~m} / \mathrm{s}$. Joe sees a lightning flash, and then hears the thunder 12 seconds later. To the nearest tenth of a kilometre, how far away is Joe from the lightning flash?
(A) 3.0
(B) 3.5
(C) 4.0
(D) 4.5
(E) 5.0
Since the sound of thunder travels at $331 \mathrm{~m} / \mathrm{s}$ and the thunder is heard 12 seconds after the lightning flash, then Joe is $12 \mathrm{~s} \times 331 \mathrm{~m} / \mathrm{s}=3972 \mathrm{~m}=3.972 \mathrm{~km}$ from the lightning flash, or, to the nearest tenth of a kilometre, $4.0 \mathrm{~km}$.

ANSWER: (C)