RRB NTPC 2020 PYQs

Question 1

Invertebrates do NOT include:

Accepted Answer

Invertebrates are animals without a backbone. Reptiles possess a backbone, classifying them as vertebrates. Molluscs, arachnids, and insects are all invertebrates.

Question 2

Find the least number, which must be subtracted from 60065 to make it a perfect square.

Accepted Answer

Find the square root of 60065. The nearest perfect square less than 60065 is 245^2 = 60025. Subtract 60025 from 60065 to get 40.

Question 3

In which year was The Environment (Protection) Act passed by the Parliament of India?

Accepted Answer

The Environment (Protection) Act was enacted by the Parliament of India in 1986. This act provides for the protection and improvement of the environment.

Question 4

According to which law, at a constant temperature, the volume of a gas is inversely proportional to pressure?

Accepted Answer

Boyle's Law states that for a fixed amount of gas at constant temperature, pressure and volume are inversely proportional. This is a direct recall of the law.

Question 5

The least number that when divided by 144, 108 and 72 leaves the remainder 3 in each case is

Accepted Answer

Find the LCM of 144, 108, and 72, which is 432. Add the common remainder, 3, to the LCM. So, 432 + 3 = 435.

Question 6

The Nipah virus outbreak in 2018 took place in:

Accepted Answer

The Nipah virus outbreak in 2018 was a significant health event that occurred in the state of Kerala, India. This is a direct factual recall.

Question 7

How many members are there in Rajya Sabha?

Accepted Answer

The maximum strength of the Rajya Sabha is fixed at 250 members. Of these, 238 are representatives of states and union territories, and 12 are nominated by the President.

Question 8

Which of the following countries is NOT a permanent member of United Nations Security Council?

Accepted Answer

The five permanent members of the UN Security Council are China, France, Russia, the United Kingdom, and the United States. Japan is not a permanent member.

Question 9

Where is the headquarters of United Nations Security Council located?

Accepted Answer

The United Nations Security Council (UNSC) is one of the six principal organs of the United Nations, and its headquarters are located in New York City, USA.

Question 10

In Aug 2020, who was selected as the next Chairman of Steel Authority of India Limited?

Accepted Answer

Soma Mondal was selected as the next Chairman of Steel Authority of India Limited (SAIL) in August 2020, making her the first woman to head the steel giant.

Question 11

A mixture contains acid and alcohol in the ratio of 3 : 2. On adding 10 litres of alcohol in mixture, the ratio of acid to alcohol becomes 3 : 5. The quantity of acid (in litres) in the original mixture was:

Accepted Answer

Let acid be 3x and alcohol be 2x. After adding 10L alcohol, the new ratio is 3x / (2x + 10) = 3/5. Solving for x gives x = 10. Original acid quantity is 3x = 3 * 10 = 30 litres.

Question 12

A shopkeeper sold two toys for Rs. 990 each. On the first toy he gained 10% and on the second he lost 10%. Find the total percentage gain or loss.

Accepted Answer

When two items are sold at the same price, one at x% gain and other at x% loss, there is always a loss of (x/10)^2 %. Here, x=10, so loss is (10/10)^2 = 1% loss.

Question 13

If a + b = 10 and a2+ b2= 68 find a3+ b3.

Accepted Answer

First, find ab using (a+b)² = a²+b²+2ab. Then, use the identity a³+b³ = (a+b)(a²+b²-ab) to calculate the final value.

Question 14

X and Y together can complete a piece of work in 12 days, Y and Z can do it 18 days and X and Z can complete the same work in 15 days. If X, Y and Z can together complete the work, approximately how many days will be required to complete the work?

Accepted Answer

Calculate individual efficiencies: (X+Y)=1/12, (Y+Z)=1/18, (X+Z)=1/15. Summing these gives 2(X+Y+Z) efficiency. Divide by 2 to get (X+Y+Z) efficiency, then take the reciprocal for total days.

Question 15

A man invested 1/2 of his capital at 5% rate of interest per annum, 1/3 of his capital at 8% per annum and the remaining at 10% rate of interest per annum. His total income from the three investments is Rs. 820.00 in a year. The total capital invested is:

Accepted Answer

Let total capital be P. Calculate interest for each part: P/2 at 5%, P/3 at 8%, and remaining P/6 at 10%. Sum these interests and equate to 820 to find P.

Question 16

The train fare, bus fare and air fare between 2 places are in the ratio 5 : 8 : 12, the number of passenger travelled by them is in the ratio 3 : 4 : 5 and the total fare collected on a particular day for these modes of transportation for a single trip is Rs. 1,07,000. Find the fare collected from the air passengers.

Accepted Answer

Multiply fare ratio by passenger ratio for each mode: Train (5*3=15), Bus (8*4=32), Air (12*5=60). Total ratio sum = 15+32+60 = 107. Air fare = (60/107) * 107000 = Rs. 60,000.

Question 17

The base of an isosceles triangle in 8 cm and one of its equal sides is 5 cm. The height of the vertex opposite to the base from the base is:

Accepted Answer

The height bisects the base into two 4 cm segments. Using Pythagoras theorem (5^2 - 4^2 = height^2), we get height = 3 cm.

Question 18

2(sin6θ + cos6θ) - 3(sin4θ + cos4θ) is equal to:

Accepted Answer

Use identities: sin⁶θ + cos⁶θ = 1 - 3sin²θcos²θ and sin⁴θ + cos⁴θ = 1 - 2sin²θcos²θ. Substitute these into the expression and simplify to get 2(1 - 3sin²θcos²θ) - 3(1 - 2sin²θcos²θ) = 2 - 6sin²θcos²θ - 3 + 6sin²θcos²θ = -1.

Question 19

The smallest square number which is exactly divisible by 12, 15 and 18 is:

Accepted Answer

Find the LCM of 12, 15, and 18, which is 180. To make 180 a perfect square, multiply it by 5 to get 900, as 180 = 2² × 3² × 5.

Question 20

To create Scientific temperament, innovation amongst the Indian students, Central Government started an ATL lab. What is the full form of ATL?

Accepted Answer

ATL stands for Atal Tinkering Lab, an initiative by NITI Aayog to foster curiosity, creativity, and imagination in young minds across India.