Question

A pollution filtering machine is installed in a factory, on a floor with area 2500 sq. feet. The machine is expected to filter at least 3500 liters of air and water. It filters air at the rate of 600 liters per hour and it filters water at the rate of 250 liter per hour. Which of the following inequalities represents the number of hours the machine should filter air (A) and water (W) to meet the expectation?

• A. $600A+250W\ge 3500$
• B. $600A+250W\le 3500$
• C. $250A+600W\ge 3500$
• D. $250A+600W\le 3500$

Answer 1

The correct option is A $600A+250W\ge 3500$

Step 1 : Underline the keywords

A pollution filtering machine is installed in a factory, on a floor with area 2500 sq. feet. The machine is expected to filter at least 3500 liters of air and water. It filters air at the rate of 600 liters per hour and it filters water at the rate of 250 liter per hour. Which of the following inequalities represents the number of hours the machine should filter air (A) and water (W) to meet the expectation.

Step 2 : Recognize the variable

Number of hours to filter Air : A
Number of hours to filter Water : W

Step 3 : Decipher the relation between the variables

Amount of air filtered : 600A [Eliminate option C and D!]
Amount of water filtered : 250W
Now, all you need to do is figure out the inequality.

Step 4 : Decide the inequality.

Look out for words :Atleast
Therefore, the inequality is $600A+250W\ge 3500$
Hence, option A is correct.