Answer:
[tex]\frac{1}{3}[/tex] km/s or 0.3333333 km/s (you can round to whatever value you need to)
Step-by-step explanation:
We can write the rate at which sound travels as the fraction [tex]\frac{19.8}{1}[/tex] km/min
As there are 60 seconds in a minute, we can replace the 1 min with 60 seconds in this fraction [tex]\frac{19.8}{60}[/tex] km/s.
When reduces, this fraction gives us: [tex]\frac{1}{3}[/tex] km/s or 0.3333333 km/s (you can round to whatever value you need to)
