alanforde800Maximus wrote:
If snow accumulation increased at a constant rate of 30 millimeters per hour during a certain snowstorm, how many seconds did it take for snow accumulation to increase by 1 millimeter?
a) 1/120
b) 1/60
c) 1/20
d) 20
e) 120
I suspect the trap answer is A. It is easy to overlook units.
Shortcut: 1 hour = 3600 seconds
\(\frac{30mm}{1hour}=\frac{30mm}{3600secs}=\frac{1mm}{120secs}\)Units are not the same. The answer is not A. In 120 seconds, 1mm of snow will accumulate.
Answer E
No shortcut:
\((\frac{30mm}{1hour}*\frac{1hour}{60mins}*\frac{1min}{60secs})=\frac{30mm}{(60*60)secs}=\frac{30mm}{3600secs}\)In the parentheses, hours and minutes cancel. Factor out 30, write the final units:
\(\frac{1mm}{120secs}\)Answer E
close
70% (01:09) correct 
