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🇮🇳 RRB Group D · flashcards
RRB Group D Mathematics (Arithmetic) Flashcards
50 question-and-answer cards covering Mathematics (Arithmetic) as it is examined in RRB Group D. 24 of them are printed below, taken from across the deck — no signup, no paywall on the preview.
24 sample cards from the Mathematics (Arithmetic) deck
Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.
If a:b = 2:3 and b:c = 4:5, what is a:b:c?
a:b:c = 8:12:15. Make b common: a:b = 8:12 (×4), b:c = 12:15 (×3), so a:b:c = 8:12:15.
How do you convert a fraction or ratio to a percentage?
Multiply by 100 and add the % sign. E.g. 3/4 = (3/4)×100 = 75%. To convert a % to a fraction, divide by 100.
How do you find x% of a value N?
x% of N = (x/100) × N. E.g. 20% of 250 = (20/100)×250 = 50.
What is the formula for percentage increase or decrease?
Percentage change = (Change in value / Original value) × 100. Increase if positive, decrease if negative.
If a number is increased by 25%, by what % must it be decreased to return to the original?
20%. Increasing by 25% gives 1.25×; to undo, decrease = (0.25/1.25)×100 = 20%.
What is the formula for the average (arithmetic mean) of a set of numbers?
Average = (Sum of all observations) / (Number of observations).
What is the average of the first n natural numbers?
Average = (n+1)/2. (Sum = n(n+1)/2, divided by n.)
If the average of n quantities changes when one is added/removed, how do you find the new value?
New sum = old average × old count ± changes; new average = new sum / new count. Use: change in total = change in average × number of items affected.
What is the average speed for a round trip at speeds x and y over the same distance?
Average speed = 2xy/(x+y), the harmonic mean (not the simple average of x and y).
What is the Rule of Alligation?
It finds the ratio in which two ingredients at given prices/concentrations must be mixed to produce a mixture of a desired mean value: (Quantity cheaper)/(Quantity dearer) = (Dearer − Mean)/(Mean − Cheaper).
In a mixture, if x litres of pure liquid is replaced by water repeatedly n times in a vessel of capacity V, what fraction of pure liquid remains?
Remaining pure liquid = V × (1 − x/V)^n. This is the standard replacement formula.
What is the formula for profit and loss in terms of CP and SP?
Profit = SP − CP (when SP > CP); Loss = CP − SP (when CP > SP). CP = cost price, SP = selling price.
How do you calculate profit % and loss %?
Profit % = (Profit/CP) × 100; Loss % = (Loss/CP) × 100. Both are always calculated on the Cost Price.
How do you find SP from CP and profit/loss percentage?
SP = CP × (100 + Profit%)/100 for profit, or SP = CP × (100 − Loss%)/100 for loss.
What is marked price (MP) and how does discount relate to it?
MP (list price) is the price marked on an item. Discount is a reduction on MP. SP = MP × (100 − Discount%)/100; discount is always calculated on MP.
If an item is sold at the same price, one at x% profit and another at x% loss, what is the overall result?
There is always an overall loss of (x/10)² %, i.e. x²/100 %. E.g. 10% each way → 1% loss.
What is the formula for Simple Interest?
SI = (P × R × T)/100, where P = principal, R = rate % per annum, T = time in years.
What is the formula for the Amount under Simple Interest?
Amount = Principal + Simple Interest = P + (P×R×T)/100 = P(1 + RT/100).
Under simple interest, in how many years does a sum double at R% per annum?
Time to double = 100/R years (since SI must equal P, so P = P×R×T/100 → T = 100/R).
What is the formula for Compound Interest (compounded annually)?
Amount = P(1 + R/100)^T, and CI = Amount − P, where P = principal, R = rate % p.a., T = time in years.
How is the compound interest formula adjusted for half-yearly compounding?
Amount = P(1 + (R/2)/100)^(2T). The rate is halved and the number of periods is doubled. (For quarterly: R/4 and 4T.)
What is the key difference between Simple Interest and Compound Interest?
SI is calculated only on the original principal each period; CI is calculated on principal plus accumulated interest, so interest earns interest.
For 2 years, what is the difference between CI and SI on the same principal and rate?
Difference = P × (R/100)². For 2 years the CI−SI gap equals the principal times the square of the rate (as a decimal).
What is the shortcut to compute CI for 2 years as an effective rate?
Effective 2-year rate = (2R + R²/100)%. E.g. at 10% for 2 years, effective = 21%, so Amount = P × 1.21.
What this deck covers
The Mathematics (Arithmetic) deck follows the RRB Group D Mathematics (Arithmetic) syllabus — 6 chapters and 24 topics — so questions land on material that is genuinely examinable rather than trivia around it. That works out to roughly 8.3 cards per chapter.
Answers are written to be recallable, not just readable — averaging about 100 characters, which is long enough to carry the reasoning and short enough to say out loud.
A deck like this earns its keep on the second and third pass. Read the syllabus first so you know the shape of the subject, then use the cards to find the specific facts that have not stuck.
Mathematics (Arithmetic) flashcards FAQ
How many Mathematics (Arithmetic) flashcards are in this RRB Group D deck?
50 cards. This page previews 24 of them, sampled evenly across the deck so you can judge the difficulty before installing anything.
Are these RRB Group D flashcards free?
Yes. The preview here is free to read with no signup, and the full 50-card deck is free inside the Examius app.
What do the Mathematics (Arithmetic) cards cover?
They follow the RRB Group D Mathematics (Arithmetic) syllabus — 6 chapters and 24 topics — so the questions track what is actually examinable.
How should I use these flashcards?
Read the syllabus first so you know the shape of the subject, then drill the deck. Examius schedules each card with spaced repetition, so cards you keep missing come back sooner and ones you know drift further apart.