Data interpretation and caselets — quick quiz

A retail store sold four types of items: Pens, Notebooks, Calculators, and Diaries. The table below shows the number of units sold and the selling price per unit (in Rs) for each item over three months. Month 1: Pens: 120 units, Rs 25 each Notebooks: 80 units, Rs 40 each Calculators: 20 units, Rs 500 each Diaries: 100 units, Rs 30 each Month 2: Pens: 150 units, Rs 25 each Notebooks: 90 units, Rs 40 each Calculators: 25 units, Rs 480 each Diaries: 90 units, Rs 30 each Month 3: Pens: 100 units, Rs 30 each Notebooks: 110 units, Rs 45 each Calculators: 30 units, Rs 500 each Diaries: 120 units, Rs 35 each In which month did the revenue from Notebooks exceed the revenue from Diaries by the largest amount?