Answer
a.) 2 min
b.) 240 min
Work Step by Step
a.) 120 sec = 2 min
You are converting from a smaller unit to a larger unit (a second is less than a minute), so divide.
Because 60 sec = 1 min, divide by 60 and write the fraction in lowest terms
120 sec= 120 ÷ 60 = 2 min.
b.) 4 hr = 240 min
You are converting from a larger unit to a smaller unit (an hour is larger than a minute), so multiply.
Because 1 hr = 60 min, multiply by 60.
4 hr = 4 * 60 = 240 min.