General Aptitude, Reasoning and Quantitative Ability
What the domain tests
Numerical ability, logical reasoning and data interpretation, often dressed in pharmacy contexts such as dilution strengths, percentage concentrations and stock solutions. Speed matters: most items are solvable in under a minute if the right shortcut is applied.
Core rules to hold
- Percentages and successive change: a rise of a% then a fall of b% gives a net change of a − b − ab/100; always identify the base for each percentage.
- Profit and loss: mark-up is on cost price, margin on selling price - the same numbers give different answers.
- Time and work: combine rates, not times; if A alone takes a days and B alone b days, together they take ab/(a + b).
- Interest: simple interest is PRT/100; compound interest is P[(1 + R/100)^n − 1].
- Mixtures: alligation gives the ratio for blending two strengths to a target strength.
- Reasoning: series (difference, ratio, square-cube patterns), coding-decoding, blood relations, direction sense, syllogisms with Venn diagrams, seating arrangement.
Worked example
A pharmacist must blend 20% w/v and 5% w/v solutions to make a 12% w/v solution. Alligation: parts of the stronger = 12 − 5 = 7, parts of the weaker = 20 − 12 = 8, so the ratio is 7:8. To make 300 mL, take 7/15 × 300 = 140 mL of the 20% solution and 160 mL of the 5% solution. Check: (140 × 20 + 160 × 5)/300 = (2800 + 800)/300 = 12% w/v.
Traps that cost marks
Applying a percentage to the already-changed value; adding times instead of adding rates in work problems; using simple interest where compounding is specified; assuming the alligation ratio refers to final volume rather than to parts.