RRB NTPC Undergraduate CBT 1 2024 PYQs

Concept: The difference of ratio terms equals the given difference; scale up to the total.

1. Ratio $5:8:17$, total $=30$ parts.
2. Largest − smallest $=17-5=12$ parts $=78106$
3. Total $=\frac{78106}{12}\times 30=78106\times 2.5=195265$

Trick: $\frac{30}{12}=2.5$ – multiply the difference by 2.5 directly.

Answer: (D) ₹1,95,265

Concept: Distance = Speed × Time (convert the units first).

1. $54\text{km/h}=54\times \frac{5}{18}=15\text{m/s}$
2. $1.7\text{min}=1.7\times 60=102\text{s}$
3. Length $=15\times 102=1530\text{m}=1.53\text{km}$

Trick: $54\text{km/h}=0.9\text{km/min}$, so $0.9\times 1.7=1.53\text{km}$.

Answer: (C) 1.53 km

Concept: Two equal cubes joined face to face form a cuboid $2a\times a\times a$; $\text{TSA}=2(lb+bh+hl)$.

1. $l=10$, $b=5$, $h=5$ (cm)
2. $\text{TSA}=2(10\times 5+5\times 5+5\times 10)=2\times 125$
3. $=250{\text{cm}}^2$

Trick: Two cubes have 12 faces; joining hides 2, so TSA $=10a^2=10\times 25=250$.

Answer: (B) $250{\text{cm}}^2$

Concept: Convert each pipe to "tank per hour"; filling pipes are +, emptying pipes are −.

1. P fills $\frac{2}{3}$ in 24 h → full tank in $36\text{h}$; Q: $\frac{2}{3}$ in 16 h → $24\text{h}$.
2. In 4 h, P + Q fill $4(\frac{1}{36}+\frac{1}{24})=4\times \frac{5}{72}=\frac{5}{18}$ of the tank.
3. R empties $\frac{5}{18}$ in 5 h → R empties a full tank in $18\text{h}$.
4. Together: $\frac{1}{36}+\frac{1}{24}-\frac{1}{18}=\frac{2+3-4}{72}=\frac{1}{72}$ → $72\text{h}$

Trick: LCM 72 as capacity: P = 2, Q = 3, R = −4 units/h; net $=1$ unit/h → 72 h.

Answer: (A) 72 hours

Concept: Mean proportional of $a$ and $b$ $=\sqrt{ab}$.

1. $\sqrt{19\times 76}=\sqrt{19\times 19\times 4}$
2. $=19\times 2=38$

Trick: $76=4\times 19$, so the answer is $2\times 19$ without multiplying out.

Answer: (C) 38

Concept: Number to add $=$ divisor − remainder.

1. $41\times 410=16810$
2. $16809=16810-1$, so remainder $=40$.
3. Number to add $=41-40=1$

Trick: Look for a round multiple near the number: $41\times 410=16810$ is just 1 more.

Answer: (C) 1

Concept: If SP of $n$ items = CP of $m$ items, then $\frac{\text{SP}}{\text{CP}}=\frac{m}{n}$.

1. $16\text{SP}=8\text{CP}\Rightarrow \frac{\text{SP}}{\text{CP}}=\frac{8}{16}=\frac{1}{2}$
2. SP < CP → loss.
3. $\text{Loss}\%=\frac{1-\frac{1}{2}}{1}\times 100=50\%$

Trick: $\%=\frac{m-n}{n}\times 100=\frac{8-16}{16}\times 100=-50\%$ (negative = loss).

Answer: (C) $50\%$ loss

Concept: $\text{SI}=\frac{P\times R\times T}{100}$

1. $\text{SI}=\frac{400\times 4\times 5.5}{100}$
2. $=4\times 4\times 5.5=88$

Trick: $4\%$ of 400 = 16 per year; $16\times 5.5=88$.

Answer: (C) 88

Concept: Equivalent discount of $a\%$ and $b\%$ $=a+b-\frac{ab}{100}$.

1. $20+10-\frac{20\times 10}{100}$
2. $=30-2=28\%$

Trick: On ₹100: after $20\%$ → 80; after $10\%$ → 72; total discount $=28\%$.

Answer: (D) $28\%$

Concept: One day's work of C $=\frac{1}{4}-\frac{1}{17}-\frac{1}{16}$.

1. LCM of 4, 17, 16 $=272$.
2. $\frac{68-16-17}{272}=\frac{35}{272}$
3. C alone $=\frac{272}{35}=7\frac{27}{35}$ days

Trick: Total work 272 units: A = 16, B = 17, all = 68 units/day → C $=35$ units/day.

Answer: (B) $7\frac{27}{35}$ days

Concept: Trace each move on a grid; facing west, a right turn means north.

1. 325 m west → showroom; right turn → north 220 m → fitness centre.
2. Right → east 200 m; right → south 220 m: he is back on the starting line.
3. Gap from start $=325-200=125\text{m}$

Trick: The two 220 m legs cancel; only east–west matters: $325-200=125$.

Answer: (A) 125 m

Concept: Swap the signs first, then apply BODMAS.

1. $28+125\times 5-12÷3$ becomes $28-125÷5+12\times 3$
2. $=28-25+36$
3. $=39$

Trick: Rewrite the whole expression with new signs before calculating – never swap mid-way.

Answer: (C) 39

Concept: Find the single operation linking each pair.

1. $37+25=62$; $52+25=77$ → rule: add 25.
2. Check options: $81+25=106$ ✗, $69+25=94$ ✗, $64+25=89$ ✗, $46+25=71$ ✓

Trick: When both pairs show the same difference, just look for that difference in the options.

Answer: (D) 46, 71

Concept: Track each letter position and the number separately.

1. 1st letters: N, J, F, B, X, T (each −4).
2. 2nd letters: U, Q, M, I, E, A (−4); 3rd letters: B, X, T, P, L, H (−4).
3. Numbers: 63, 54, 45, 36, 27, 18 (−9).

Trick: After B, going back 4 wraps around: B → X; after E → A, after L → H.

Answer: (D) TAH 18

Concept: Compare position gaps: 1st → 2nd and 2nd → 3rd letter.

1. ORM: 15, 18, 13 → +3, −5; VYT: 22, 25, 20 → +3, −5; RUP: 18, 21, 16 → +3, −5.
2. LOI: 12, 15, 9 → +3, −6 ✗

Yaad rakhein: EJOTY – E5, J10, O15, T20, Y25 helps convert letters fast.

Answer: (D) LOI

Concept: Check the differences between consecutive terms.

1. Differences: 17, 21, 25, 29, 33 (each +4).
2. Next $=145+33=178$

Trick: Second differences constant (+4) → next difference is simply last + 4.

Answer: (D) 178

Concept: Check the gap inside each cluster and between the clusters.

1. SV-UX: S+3 = V, S+2 = U, U+3 = X. DG-FI and BE-DG follow the same +3 / +2 / +3 pattern.
2. EI-HK: E+4 = I ✗ (gap is 4, not 3).

Trick: Check the internal gap of the first cluster first – it exposes the odd one fastest.

Answer: (D) EI-HK

Concept: Fix the definite positions first, then test the cases.

1. S = 3rd from left, Z = 8th (right end).
2. Only U between S and W: W at 5 (U at 4) or W at 1 (U at 2). If W = 1, V must be at 2, which is U – impossible. So U = 4, W = 5.
3. T next to S and Y → T = 2, Y = 1; V next to W → V = 6; X = 7.
4. Order: Y T S U W V X Z → right of W: V, X, Z = 3.

Trick: Use "only U sits between" to make two cases and kill one quickly.

Answer: (A) Three

Concept: Check the differences between consecutive terms.

1. Differences: 88, 96, 104, 112 (each +8).
2. Next difference $=120$ → $842+120=962$

Trick: Differences rising by a fixed amount → keep adding that amount.

Answer: (C) 962

Concept: Draw the least-overlap Venn diagram; a conclusion follows only if it is true in every possible diagram.

1. Forests lie inside Hills; Deserts overlap Hills.
2. I: "All hills are forests" – Hills can be bigger than Forests → not certain ✗.
3. II: "Some deserts are hills" – conversion of "Some hills are deserts" ✓.

Yaad rakhein: "Some A are B" ⇔ "Some B are A" always; "All A are B" never gives "All B are A".

Answer: (A) Only Conclusion II follows