*Question T5B12:
Which is equal to 28400 kHz?*  

*Correct Answer is  D: 28.400 MHz*  

### AI Response: (may contain errors)  

To determine which option is equal to 28400 kHz, we need to convert kilohertz (kHz) to megahertz (MHz) and understand the relationships between these units.

1. **Correct Answer: 28.400 MHz**
   - To convert kHz to MHz, we use the conversion factor:
     $$1 \text{ MHz} = 1000 \text{ kHz}$$
   - Therefore, to convert 28400 kHz to MHz:
     $$\text{Frequency in MHz} = \frac{28400 \text{ kHz}}{1000} = 28.400 \text{ MHz}$$
   - This shows that 28400 kHz is indeed equal to 28.400 MHz.

2. **Why the Other Choices are Incorrect:**
   - **A: 28.400 kHz**
     - This is incorrect because it does not match the conversion. 28.400 kHz is much lower than 28400 kHz.
   - **B: 2.800 MHz**
     - This is also incorrect. Converting 2800 kHz to MHz gives:
       $$\frac{2800 \text{ kHz}}{1000} = 2.800 \text{ MHz}$$
     - This is not equal to 28400 kHz.
   - **C: 284.00 MHz**
     - This is incorrect as well. Converting 284000 kHz to MHz gives:
       $$\frac{284000 \text{ kHz}}{1000} = 284.00 \text{ MHz}$$
     - This is much higher than 28400 kHz.

3. **Useful Formulas or Rules of Thumb:**
   - Remember the conversion between kHz and MHz:
     $$\text{Frequency in MHz} = \frac{\text{Frequency in kHz}}{1000}$$
   - This conversion is essential for understanding frequency bands in amateur radio and ensuring you can accurately interpret frequency values.

In summary, the correct answer is 28.400 MHz because it accurately reflects the conversion from 28400 kHz, while the other options do not match this value.