This is an independent topic guide, not the official syllabus. Compare it with the current paper outline and rules published by the examination authority.
01 / UNDERSTANDING
Learning objectives
Study component balance, weighted concentration and well-mixed replacement. Make the additive-volume assumption explicit and derive alligation from balance rather than treating its cross as unexplained magic.
02 / UNDERSTANDING
The concept in context
A mixture percentage is a component amount divided by the mixture’s total amount. When combining solutions, calculate the component in each portion and add both the component amounts and total volumes under the stated additive-volume assumption. Equal percentages should not be averaged directly when the mixed volumes are unequal.
03 / UNDERSTANDING
A worked learning case
Original educational case. Ten litres of a 20% solution contain two litres of the named component. Twenty litres of a 50% solution contain ten litres. Assuming volumes add, the mixture contains twelve litres in thirty litres, or 40%. The larger, stronger portion receives more weight, so the result is above the unweighted mean of 35%.
ORIGINAL EDUCATIONAL PRACTICE
Try it before you check.
Original practice: Combine 5 litres at 20% concentration with 5 litres at 40%, assuming additive volumes. What is the final concentration?
Show the answer and reasoning
30%.
The portions contain one litre and two litres of the component respectively, giving three litres in a total of ten litres. The concentration is 3/10 × 100 = 30%. Equal volumes make the simple mean valid in this particular case; unequal volumes would require different weights rather than the same shortcut.
Two traps to watch for.
- Averaging concentrations despite unequal mixture quantities.
- Removing a mixed portion as if only one component leaves.
YOUR TOPIC-SPECIFIC LEARNING MAP
Your revision map
Calculate component amount before mixing.
Track total volume separately.
Explain why the resulting concentration lies between inputs.
Explain the idea, apply it to a new situation, then check what changed in your reasoning.
BANKERS TUTORIAL · SOURCE NOTES
Keep the source alongside your notes.
Official links provide subject context and authoritative reference material. This guide’s explanation, scenario and question are original Bankers Tutorial learning content.
- sbi.bank.in https://sbi.bank.in/web/careers/current-openings
- sbi.bank.in https://sbi.bank.in/webfiles/uploads/files_2627/09/SBI_JA-Customer_Support_Sales-IH_Pre-2026-27_Eng.pdf
For SBI preparation, check the current official notice before relying on changing dates, rules or examination requirements.
