Vishal donates blood thrice in 2 years - each time 350 ml. How many litres of…

Concept: When a quantity accumulates at a fixed rate over repeating time periods, the total amount over a longer duration equals the amount per period multiplied by the number of such periods that fit into the longer duration.

1. Blood donated in one 2-year period = 3 donations x 350 ml = 1050 ml = 1.05 litres.

2. Number of 2-year periods in 6 years = 6 divided by 2 = 3.

3. Total blood donated in 6 years = 1.05 litres x 3 = 3.15 litres.

Cross-check: Equivalently, the total number of donations in 6 years = 3 donations x 3 periods = 9 donations; 9 x 350 ml = 3150 ml = 3.15 litres, confirming the answer.