How many minutes are there in $2.8$ hours?

Hint: We know that 1 hour is equivalent to 60 minutes. So to calculate the number of minutes in 2.8 hours, we have to apply a unitary method and multiply 2.8 by 60. Do the following calculation to get the final answer.

Complete step-by-step solution:
We have to calculate the number of minutes in 2.8 hours.
We already know that 1 hour consists of 60 minutes.
$ \Rightarrow 1{\text{ hour}} = 60{\text{ minutes}}$
To calculate the number of minutes in 2.8 hour we have to apply a simple unitary method.
If the unit hour contains 60 minutes then the number of minutes in 2.8 hour will be the product of 2.8 and 60. Doing so, we’ll get:
$
   \Rightarrow 2.8{\text{ hour}} = 2.8 \times 60{\text{ minutes}} \\
   \Rightarrow 2.8{\text{ hour}} = 168{\text{ minutes}}
 $

Thus 2.8 hours contains 168 minutes.

Additional Information: We also know that 1 minute contains 60 seconds.
$ \Rightarrow 1{\text{ minute}} = 60{\text{ seconds}}$
So we can also calculate the number of seconds in an hour by applying the same unitary method.
If a unit minute contains 60 seconds then the number of seconds in 1 hour i.e. 60 minutes will be the product of 60 seconds and 60 minutes.
$
   \Rightarrow 1{\text{ hour}} = 60{\text{ minute}} = 60 \times 60{\text{ seconds}} \\
   \Rightarrow 1{\text{ hour}} = 60{\text{ minute}} = 3600{\text{ seconds}}
 $
Thus 1 hour is equivalent to 60 minutes which is also equivalent to 3600 seconds.

Note: Using unitary methods, we solve the problem by first finding the value of one unit and then finding the required value by multiplying the single unit value with necessary value. This method is widely used in time and distance problems and in time and work problems.