Step-by-step explanation:
Let's take the unit ratio of weight to length:
[tex] \frac{15 \: pounds}{4 \: feet} = 3.75 \frac{pound}{feet}[/tex]
Now that we have the unit ratio, let's multiply it to the similar pipe which is 7 feet long.
[tex]3.75 \frac{pounds}{feet} \times 7 \: feet = 26.25 \: pounds[/tex]
