Mathematics15 mins read

Complete Numerical Aptitude Formula Sheet

Exam Target: Bihar Police Sub-Inspector (Bihar Police SI)

Quick reference guide for crucial formulas in Arithmetic, Algebra, Geometry, and Trigonometry for Railway, SSC, and Banking exams.

Bihar Police Sub-Inspector (Bihar Police SI) follows a 100 Q | 120 Min | Prelims pattern, with Mathematics as one of its scored sections alongside General Studies, General Hindi, General Science. The reference notes below apply directly to the Mathematics portion of Bihar Police SI's syllabus.

1. Percentages and Fractions conversion

Understanding percentage fractions is key to solving DI and Simplification questions fast. Key equivalents: 1/2 = 50%, 1/3 = 33.33%, 1/4 = 25%, 1/5 = 20%, 1/6 = 16.67%, 1/7 = 14.28%, 1/8 = 12.5%, 1/9 = 11.11%, 1/11 = 9.09%, 1/12 = 8.33%.

2. Profit, Loss, and Discount

• Profit = Selling Price (SP) - Cost Price (CP) • Loss = CP - SP • Profit % = (Profit / CP) * 100 • Loss % = (Loss / CP) * 100 • Marked Price (MP) = CP + Markup • Discount = MP - SP • Discount % = (Discount / MP) * 100 • SP = MP * (100 - Discount%) / 100.

3. Simple and Compound Interest

• Simple Interest (SI) = (P * R * T) / 100 • Amount (Simple Interest) = P + SI • Compound Interest (CI) = P * [ (1 + R/100)^T - 1 ] • Amount (Compound Interest) = P * (1 + R/100)^T • Difference between CI and SI for 2 Years = P * (R / 100)^2 • Difference between CI and SI for 3 Years = P * (R / 100)^2 * (3 + R/100).

4. Time, Speed, and Distance

• Speed = Distance / Time • Convert km/hr to m/s: Multiply by 5/18 • Convert m/s to km/hr: Multiply by 18/5 • Average Speed (when distances are equal) = 2xy / (x + y), where x and y are the two speeds. • Relative Speed (same direction) = u - v (where u > v) • Relative Speed (opposite direction) = u + v.

5. Time and Work

• Work = Efficiency * Time • If A does a piece of work in D1 days and B in D2 days, then together they do it in (D1 * D2) / (D1 + D2) days. • MDH Formula: (M1 * D1 * H1) / W1 = (M2 * D2 * H2) / W2, where M = Men, D = Days, H = Hours, W = Work.

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