Final answer:
The ratio of glass to cardboard in the recycling bin is 4:1.
Step-by-step explanation:
To find the ratio of glass to cardboard in the recycling bin, we need to compare the mass of glass to the mass of cardboard. The recycling bin contains 2kg of glass and 500g of cardboard. To simplify the ratio, we need to convert the mass of cardboard to kilograms by dividing it by 1000. So, the mass of cardboard is 0.5kg.
Now, we can write the ratio of glass to cardboard as 2:0.5. To simplify further, we divide both numbers by their greatest common factor, which is 0.5. This gives us a simplified ratio of 4:1.