A 20 kg mixture of wheat and husk contains 5% husk.\nHow many kilograms of husk must be added to this mixture so that in the new mixture, husk content becomes 20% by weight?

Introduction:
This is a percentage-by-weight mixture adjustment problem. When only husk is added, the amount of wheat stays constant, and the husk amount increases along with total weight. We compute initial husk weight, then solve for added husk so that husk becomes 20% of the new total weight.

Given Data / Assumptions:

• Total mixture initially = 20 kg
• Initial husk percentage = 5%
• Only husk is added
• Target husk percentage = 20%

Concept / Approach:
Initial husk = 5% of 20. Let x kg husk be added.\nThen new husk = initial husk + x and new total = 20 + x.\nTarget condition: (husk)/(total) = 0.20.

Step-by-Step Solution:
Initial husk = 5% of 20 = (5/100)*20 = 1 kgLet husk added = x kgNew husk = 1 + xNew total = 20 + xTarget: (1 + x) / (20 + x) = 0.201 + x = 0.20(20 + x) = 4 + 0.20xx - 0.20x = 4 - 10.80x = 3x = 3.75 kg

Verification / Alternative Check:
After adding 3.75 kg husk:\nHusk = 1 + 3.75 = 4.75 kg.\nTotal = 20 + 3.75 = 23.75 kg.\nHusk% = 4.75/23.75 = 0.20 = 20%, correct.

Why Other Options Are Wrong:
2.75 kg or 3.25 kg: husk% remains below 20%.4.75 kg or 5.75 kg: husk% becomes greater than 20%.

Common Pitfalls:
Taking 20% of 20 kg directly (ignoring that total changes after adding).Treating percentage increase as additive without forming an equation.Forgetting to compute initial husk amount correctly.

Final Answer:
3.75 kg