Final answer:
All the provided statements are correct. They accurately reflect standard conversion factors for inches to centimeters, and feet to inches or centimeters.
Step-by-step explanation:
To determine which statement is correct regarding length conversions, we need to apply the standard conversion factors. The statement 1 in. = 2.54 cm is a defined conversion and it is correct. Let's evaluate the remaining statements given this conversion factor:
- 7 in. = 17.78 cm: To verify this, multiply 7 inches by the conversion factor (7 in. × 2.54 cm/in.). The result is indeed 17.78 cm, which makes this statement correct.
- 1 ft = 12 in.: This is another standard conversion factor, and it is correct. There are 12 inches in a foot.
- 7 ft = 213.36 cm: To convert feet to centimeters, first convert feet to inches (7 ft × 12 in./ft = 84 in.) and then convert inches to centimeters (84 in. × 2.54 cm/in.). The result is 213.36 cm, which confirms this statement is correct.