Questions

Presidential elections are held every four years, in years divisible by four, in which electors for President are chosen by the method in the country.

Coal production (weight: 4.38 %) increased by 12.0 % in June 2016 over June 2015. Its cumulative index during April to June 2016-17 increased by 5.4% over corresponding period of previous year.Natural Gas

The Natural Gas production(weight: 1.71 %) decreased by 4.5 % in June 2016 over June 2015. Its cumulative index during April to June 2016-17 declined by 6.1 % over the corresponding period of previous year.Refinery Products (93% of Crude Throughput)

Petroleum Refinery production(weight: 5.94%) increased by 3.5 % in June 2016 over June 2015. Its cumulative index during April to June 2016-17 increased by 7.1 % over the corresponding period of previous year.Fertilizers

Fertilizer production(weight: 1.25%)increased by 9.8 % in June 2016 over June 2015. Its cumulative index during April to June 2016-17 increased by 11.0 % over the corresponding period of previous year.

The error lies in the first part of the sentence. After superlative adjectives, majorly two prepositions are used: of and in. We use in with a singular word referring to a place or group. Eg: I am the happiest woman in the world. We use of before plurals, before time periods such as year/month. Eg: Sunday is the best day of the week. Here, in this case, the subject is the 'school', thus, it should be 'in the school'.