RRB NTPC Undergraduate CBT 1 2024 PYQs

Concept: $\text{HCF}\times \text{LCM}=\text{product of the two numbers}$.

1. $11\times 330=66\times x$
2. $x=\frac{3630}{66}=55$

Trick: Other number must be a multiple of HCF 11 dividing 330 → 55.

Answer: (B) 55

Concept: Find each pipe's full-tank time, then add rates (emptying pipe negative).

1. P: $\frac{3}{8}$ in 21 h → full in $21\times \frac{8}{3}=56$ h; Q: $\frac{2}{7}$ in 16 h → $56$ h.
2. In 2 h: $2(\frac{1}{56}+\frac{1}{56})=\frac{1}{14}$ tank filled.
3. R empties $\frac{1}{14}$ in 3 h → empties full tank in 42 h.
4. Together: $\frac{1}{56}+\frac{1}{56}-\frac{1}{42}=\frac{3+3-4}{168}=\frac{1}{84}$ → 84 h.

Trick: Take tank $=168$ units: P = 3, Q = 3, R = −4 per hour → net 2 → $\frac{168}{2}=84$ h.

Answer: (D) 84 hours

Concept: Pythagoras: ${\text{base}}^2+{\text{height}}^2={\text{hypotenuse}}^2$; area $=\frac{1}{2}\times \text{base}\times \text{height}$.

1. Sides $x$ and $2x$: $x^2+4x^2={15}^2$
2. $5x^2=225\Rightarrow x^2=45$
3. Area $=\frac{1}{2}\times x\times 2x=x^2=45{\text{cm}}^2$

Trick: No need to find $x$ – area equals $x^2$ directly.

Answer: (C) 45

Concept: Equal terms with opposite signs cancel; then simplify the complex fraction.

1. $\frac{5}{3}$ and $-\frac{5}{3}$ cancel.
2. $1+\frac{5}{6}=\frac{11}{6}$
3. $\frac{1}{\frac{11}{6}}=\frac{6}{11}$

Trick: Spot cancellations before computing.

Answer: (B) $\frac{6}{11}$

Concept: $\text{Average}=\frac{\text{sum}}{\text{count}}$.

1. Sum $=40+49+56+76+38=259$
2. Average $=\frac{259}{5}=51.8\text{kg}$

Trick: Assume 50: deviations $-10,-1,+6,+26,-12$ sum $=9$ → $50+\frac{9}{5}=51.8$.

Answer: (D) 51.8

Concept: Profit ratio = capital × time ratio.

1. $M+N=4920,M-N=328\Rightarrow M=2624,N=2296$ → ratio $8:7$
2. $\frac{3m}{7n}=\frac{8}{7}\Rightarrow 3m=8n$ (capitals $m,n$)
3. $m=n+50000\Rightarrow 3n+150000=8n\Rightarrow n=30000$
4. $m=80000$

Trick: $2624:2296$ — divide both by 328 → $8:7$.

Answer: (C) ₹80,000

Concept: Profit = total SP − total CP (broken items give no revenue).

1. Bottles left $=50-28=22$
2. SP $=22\times 5.80=127.60$
3. Profit $=127.60-50=77.60$

Trick: Cost stays ₹50 even though bottles broke.

Answer: (D) ₹77.60

Concept: Combined average $=\frac{\text{total runs}}{\text{total matches}}$.

1. Runs in 23 matches $=23\times 42=966$
2. Runs in 10 matches $=130$
3. Average $=\frac{1096}{33}\approx 33.21$

Trick: Answer must lie between 13 and 42, nearer 42 (more matches) → only 33.21 fits the exact division.

Answer: (C) 33.21

Concept: Simplify the complex fraction and combine like fractions.

1. $\frac{1}{1+\frac{5}{6}}=\frac{6}{11}$
2. $\frac{4}{5}-\frac{2}{5}=\frac{2}{5}$
3. $\frac{2}{5}+\frac{6}{11}=\frac{22+30}{55}=\frac{52}{55}$

Trick: Group same-denominator fractions first.

Answer: (A) $\frac{52}{55}$

Concept: Interior + exterior $={180}^{\circ }$; number of sides $n=\frac{{360}^{\circ }}{\text{exterior}}$.

1. $I+E={180}^{\circ },I-E={120}^{\circ }$
2. $2E={60}^{\circ }\Rightarrow E={30}^{\circ }$
3. $n=\frac{360}{30}=12$

Trick: Exterior $=\frac{180-\text{difference}}{2}$.

Answer: (B) 12

Concept: Find the position shift of each letter (A=1 … Z=26).

1. F→I (+3), K→P (+5), P→S (+3), X→C (+5)
2. REBR→UJEW: +3, +5, +3, +5 ✓
3. ATKG: A+3=D, T+5=Y, K+3=N, G+5=L → DYNL

Trick: Alternate pattern +3, +5; wrap after Z (X+5 = C).

Answer: (D) DYNL

Concept: Trace the path on a grid; a right turn from West is North, from North is East, from East is South.

1. Y → 10 km West → 18 km North → 10 km East: now 18 km north of Y.
2. Then 15 km South: Z is $18-15=3\text{km}$ north of Y.
3. To return: 3 km towards South.

Trick: The two 10 km legs cancel; only $18-15$ matters.

Answer: (A) 3 km towards south

Concept: Common letters of two words share the common digits (order of digits may be jumbled).

1. CLAM = {1,5,8,7}, LOAM = {4,8,7,5}
2. Common letters L, A, M ↔ common digits 5, 8, 7
3. Left over: C = 1 and O = 4

Trick: Remove common letters and digits — the leftovers pair up.

Answer: (A) 4

Concept: Check the gaps between consecutive letters.

1. HKO: H+3=K, K+4=O
2. DGK: +3, +4; BEI: +3, +4
3. ORW: O+3=R, R+5=W → different

Trick: Write positions: O15 R18 W23 → gaps 3, 5.

Answer: (C) ORW

Concept: Replace symbols first, then apply BODMAS.

1. $12-2+49\times 7÷5$ becomes $12\times 2-49÷7+5$
2. $=24-7+5=22$

Trick: Swap all signs in one go before calculating.

Answer: (A) 22

Concept: Number positions 1 (bottom) to 7 (top) and fix the definite clues first.

1. Only E above V → E = 7, V = 6. Three boxes below X → X = 4.
2. Two boxes between X and W → W = 1 (7 is taken).
3. The box below G and above U (named H in the statement; the only remaining box is F) → U = 2, F = 3, G = 5.
4. Second from bottom = U.

Trick: Fill extreme positions (top/bottom) first — they leave fewest choices.

Answer: (C) U

Concept: Find the position shift of each letter.

1. F+4=J, R+3=U, U+4=Y, Z+3=C
2. VDKL→ZGOO: +4, +3, +4, +3 ✓
3. HMWU: H+4=L, M+3=P, W+4=A, U+3=X → LPAX

Trick: Pattern +4, +3, +4, +3 with wrap-around (W+4 = A).

Answer: (A) LPAX

Concept: Each letter moves +11 positions to the corresponding letter of the next cluster (cyclic).

1. J+11=U, U+11=F, O+11=Z → JUO→UFZ
2. Same for UFZ→FQK→QBV
3. QBV: Q+11=B, B+11=M, V+11=G → BMG

Trick: Here the next cluster also starts with the previous 2nd letter: J U → U F → F Q → Q B → B M.

Answer: (B) BMG

Concept: Replace letters by signs, then use BODMAS.

1. $11\times 3+20-93÷3$
2. $=33+20-31=22$

Trick: Do ÷ and × first: $93÷3=31$.

Answer: (D) 22

Concept: Look at differences between consecutive terms.

1. Differences: 1, 8, 27, 64 = $1^3,2^3,3^3,4^3$
2. Next difference $5^3=125$
3. $610+125=735$

Trick: Differences as cubes: $1,8,27,64,125$.

Answer: (A) 735