Question

A piece of ribbon is $125cm$ long. Its length cannot be expressed as ________.

• A. $1.25m$
• B. $1250mm$
• C. $12.5km$
• D. $1m25cm$

Answer 1

The correct option is C

$12.5km$

Given: length of ribbon $\left(l\right)=125cm$

Option A: $1.25m$

$$\begin{gathered} 1m=100cm \\ 1cm=\frac{1}{100}m \\ 125cm=\frac{125}{100}m \\ 125cm=1.25m \end{gathered}$$

Hence, this option is correct.

Option B: $1250mm$

$$\begin{gathered} 1cm=10mm \\ 125cm=125\times 10mm \\ 125cm=1250mm \end{gathered}$$

Hence, this option is correct.

Option C: $12.5km$

$$\begin{gathered} 1km=1000m \\ 1m=100cm \\ 1cm=\frac{1}{100}m \\ 1cm=\frac{1}{100000}km \\ 125cm=\frac{125}{100000}km \\ 125cm=0.00125km \end{gathered}$$

Hence, this option is not correct.

Option D: $1m25cm$

$$\begin{gathered} 1m=100cm \\ 1m25cm=100cm+25cm \\ 1m25cm=125cm \end{gathered}$$

Hence, this option is also correct.

$125cm$cannot be expressed as $12.5km.$

Final Answer: Option C