Question

Iron is much denser than a feather. yet, a particular sample of feathers weighs more than a sample of iron. explain how this is possible.

Answer 1

Answer is: density doesn't affect on weigh.
Density of a substance is its mass per unit volume, density is defined as mass divided by volume (d = m/V).
Weight is force on the object due to gravity. Weight is product of the mass of substance and the magnitude of the local gravitational acceleration (W = mg). Feather can have larger mass and also weight.

Answer 2

How iron can be more dense as a feather yet more feathers can weigh more is because density and weight are two completely different things. No matter how many feathers there are it's density never changes, it's weight is able to change but not density. Therefore the density of iron is higher no matter what but may weigh less than a group of feathers.