If US and China, decide to buy carbon credits, from Spain and Ukraine to make up for their high emissions, then in how many years US, and China would be able to bring down its ratio of CO2 emission (million ton) to per capita income to world standard benchmark of 0.75. (per capita income of the given countries remain same, 0.5 CO2 emissions [million ton] is compensated by purchase of 1.25 units of carbon credit, and a country can buy carbon credit units in three lots of 15, 20 and 30 units in a single year.)
Explanation:
To bring down the ratio of CO2 emission to per capita income to meet the standard benchmark of 0.75, US and China will have to bring down their CO2 emission to (300 × 0.75) and (270 × 0.75) respectively i.e. 225 and 202.5 million tons respectively.
Hence, the amount of CO2 emission US and China have to cut down to meet the standard benchmark is (1200 – 225) and (1180 – 202.5) i.e. 975 and 977.5 million tons respectively.
To reduce 0.5 million tons of CO2 emission, a country has to purchase 1.25 units of carbon credits.
Therefore, to reduce 1 million tons of CO2 emission 2.5 units of carbon credits need to be purchased.
Hence, to reduce CO2 emission by 975 and 977.5 million tons, the amount of carbon credits that need to be purchased by the US and China are (975 × 2.5) and (977.5 × 2.5) i.e. 2437.5 and 2443.75 respectively.
The number of carbon credits that a country can buy in a year is 65 (15 + 20 + 20).
Therefore, the number of years that U.S. and China will respectively take to get the ratio to the required level is (2437.5/65) i.e. 37.5 years and (2443.75/65) i.e. 37.6.
Hence, in 38 years US and China will be able to bring down its CO2 emission to per capita income to the world standard benchmark of 0.75.
Hence, option (b).
Help us build a Free and Comprehensive Preparation portal for various competitive exams by providing us your valuable feedback about Apti4All and how it can be improved.