Which of the following is NOT a valid conversion factor?

A. [tex]\frac{12 \text { hours }}{1 \text { day }}[/tex]
B. [tex]\frac{1 \text { yard }}{3 \text { feet }}[/tex]
C. [tex]\frac{1 \text { dozen }}{12 \text { cookies }}[/tex]
D. [tex]\frac{60 \text { seconds }}{1 \text { minute }}[/tex]



Answer :

To determine which of the provided conversion factors is not valid, we need to examine each one and verify its accuracy.

1. Option a: [tex]\(\frac{12 \text{ hours}}{1 \text{ day}}\)[/tex]
- This conversion factor claims that there are 12 hours in 1 day.
- We know that there are actually 24 hours in a day.
- Thus, [tex]\(\frac{12 \text{ hours}}{1 \text{ day}}\)[/tex] is incorrect.

2. Option b: [tex]\(\frac{1 \text{ yard}}{3 \text{ feet}}\)[/tex]
- This conversion factor claims that 1 yard is equal to 3 feet.
- We know that 1 yard is indeed equal to 3 feet.
- Therefore, [tex]\(\(\frac{1 \text{ yard}}{3 \text{ feet}}\)[/tex] is correct.

3. Option c: [tex]\(\frac{1 \text{ dozen}}{12 \text{ cookies}}\)[/tex]
- This conversion factor suggests that 1 dozen is equivalent to 12 cookies.
- We know that 1 dozen is indeed equal to 12 of any items, which includes cookies.
- Therefore, [tex]\(\(\frac{1 \text{ dozen}}{12 \text{ cookies}}\)[/tex] is correct.

4. Option d: [tex]\(\frac{60 \text{ seconds}}{1 \text{ minute}}\)[/tex]
- This conversion factor states that 60 seconds is equal to 1 minute.
- We know that 1 minute is indeed 60 seconds.
- Therefore, [tex]\(\(\frac{60 \text{ seconds}}{1 \text{ minute}}\)[/tex] is correct.

After examining all the options, we can conclude that the invalid conversion factor is:

Option a: [tex]\(\frac{12 \text{ hours}}{1 \text{ day}}\)[/tex]