RRB NTPC 2021 PYQs

Question 1

Find the equation of the tangents to the circle x2+ y2= 9 at x = 2.

Accepted Answer

Substitute x=2 into the circle equation to find y=±√5. The tangent equation at (x1, y1) is xx1 + yy1 = r². So, 2x + √5y = 9 and 2x - √5y = 9 are the tangents.

Question 2

The largest four-digit number that is exactly divisible by 83 is:

Accepted Answer

The largest four-digit number is 9999. Divide 9999 by 83. The remainder is 39. Subtract this remainder from 9999 to get 9960, which is divisible by 83.

Question 3

The capacity of a cylindrical tank is 2376 m3. If the radius of the tank is 21 m, then the depth of the tank is:

Accepted Answer

The volume of a cylinder is given by V = πr²h. Substitute the given values: 2376 = (22/7) * 21² * h. Solve for h to get h = 1.71 m.

Question 4

The average weight of P, Q and R is 58 kg. If the average weight of P and Q is 54 kg and that of Q and R is 48 kg, then the weight of Q is:

Accepted Answer

Total weight of P, Q, R = 58*3 = 174 kg. Total weight of P, Q = 54*2 = 108 kg. Total weight of Q, R = 48*2 = 96 kg. Q = (P+Q) + (Q+R) - (P+Q+R) = 108 + 96 - 174 = 30 kg.

Question 5

In Computer field, What does LIFO stand for?

Accepted Answer

LIFO is a fundamental data structure principle. It stands for Last In, First Out, meaning the last element added is the first one to be removed.

Question 6

Due to 25% reduction in the price of wheat per kg, John is able to buy 5 kg more for Rs.600. What is the original price of wheat per kg?

Accepted Answer

A 25% price reduction on Rs. 600 means Rs. 150 saved, which buys 5 kg. So, the reduced price is Rs. 30/kg. The original price was Rs. 30 / (1 - 0.25) = Rs. 40/kg.

Question 7

As per a new study by Greenpeace in 2018, which is the most polluted city on earth?

Accepted Answer

According to the 2018 Greenpeace study, Gurugram was identified as the most polluted city globally. This was a widely reported environmental finding.

Question 8

When was WTO (World Trade Organization) established?

Accepted Answer

The World Trade Organization (WTO) was officially established on January 1, 1995, succeeding the General Agreement on Tariffs and Trade (GATT).

Question 9

District XYZ has 50,000 voters; out of them, 20% are urban voters and 80% rural voters. For an election, 25% of the rural voters were shifted to the urban area. Out of the voters in both rural and urban areas, 60% are honest, 70% are hardworking, and 35% are both honest and hardworking.Two candidates, A and B, contested the election. Candidate B swept the urban vote, while Candidate A found favour with the rural voters. Voters who were both honest and hardworking voted for NOTA. How many votes were polled in favour of candidate A, candidate B and NOTA, respectively?

Accepted Answer

Calculate initial urban/rural voters. Shift 25% rural to urban. Find total honest and hardworking voters (35% of 50,000 = 17,500) for NOTA. Calculate new urban/rural totals and assign votes to A and B.

Question 10

Who enjoys the power to summon, prorogue either house of Indian Parliament?

Accepted Answer

The President of India has the constitutional power to summon and prorogue both houses of Parliament, as per Article 85 of the Indian Constitution.

Question 11

Which of the following Articles of the Constitution of India provides provisions for creation of Legislative Councils in States?

Accepted Answer

Article 169 of the Indian Constitution empowers the Parliament to create or abolish Legislative Councils in states if the state assembly passes a resolution to that effect.

Question 12

How many triangles are there in the given figure?

Accepted Answer

Count individual triangles (6). Then count triangles formed by combining two smaller triangles (2). Total 6 + 2 = 8 triangles.

Question 13

The first high court of India was established in _______.

Accepted Answer

The first High Court in India was established in Calcutta (now Kolkata) in 1862 under the Indian High Courts Act, 1861.

Question 14

As of November 2020, how many nuclear power reactors are operating in India?

Accepted Answer

As of November 2020, India had 22 operational nuclear power reactors. This is a factual recall question based on current affairs.

Question 15

The movement for a separate Andhra was called:

Accepted Answer

The movement for a separate Andhra state, advocating for all Telugu-speaking regions to be united, was known as the Visalandhra movement.

Question 16

On being criticized for borrowing features from other countries for the constitution, who said the following- “Nobody holds any patent rights in the fundamental ideas of a constitution.

Accepted Answer

Dr. B.R. Ambedkar, as the chief architect of the Indian Constitution, defended its borrowing of features by stating that fundamental constitutional ideas are not patented.

Question 17

A shopkeeper purchased a machine for Rs.70,000 and spent Rs.5,000 as overhead expenditure. Had he purchased the machine at 15% less, he would have earned a profit of 15%. What is the selling price of the machine?

Accepted Answer

Total cost price is 70000 + 5000 = 75000. If purchased at 15% less, new CP = 75000 * 0.85 = 63750. With 15% profit, SP = 63750 * 1.15 = 73312.5. The question asks for the original selling price, which is not directly given. The correct answer is 74175, assuming the 15% profit is on the original cost price.

Question 18

Which of the following neighbouring countries is separated from India by a narrow channel of sea formed by the Palk Strait and the Gulf of Mannar?

Accepted Answer

Sri Lanka is geographically separated from India by the Palk Strait and the Gulf of Mannar, which are narrow channels of sea.

Question 19

Determine the smallest number which when divided by 12,16, 20, 25 and 30 leaves the same remainder 3 in each case.

Accepted Answer

Find the LCM of 12, 16, 20, 25, and 30, which is 1200. Add the remainder 3 to the LCM. So, 1200 + 3 = 1203.

Question 20

1254 + 125.4 + 12.54 + 1.254 = ?

Accepted Answer

Align the decimal points and add the numbers column by column. The sum is 1393.194. Careful alignment is key for accuracy.