If Mary weighs 120 lbs, how much does she weigh in kg, given that 2.2 lbs = 1 kg?

To convert Mary's weight from pounds to kilograms using the conversion factor of 2.2 lbs = 1 kg, you can set up the calculation as follows:

1. Start with Mary's weight: 120 lbs.

2. Use the conversion factor to find the equivalent weight in kilograms by dividing the weight in pounds by the number of pounds per kilogram:

[

\text{Weight in kg} = \frac{\text{Weight in lbs}}{2.2} = \frac{120 \text{ lbs}}{2.2}.

]

3. Performing the division gives:

[

\text{Weight in kg} \approx 54.55 \text{ kg}.

]

When rounded to the nearest whole number, 54.55 kg can be approximated as 55 kg. This calculation confirms that the correct answer is indeed 55 kg, which reflects a proper understanding of unit conversion in weights. These steps illustrate the conversion process and affirm the correct answer based on mathematical principles.