RRB NTPC 2021 PYQs

Question 1

What is the other name of Newton's first law of motion?

Accepted Answer

Newton's first law of motion is also known as the Law of Inertia. It states that an object will remain at rest or in uniform motion unless acted upon by an external force.

Question 2

In which part of a neuron is information acquired?

Accepted Answer

Dendrites are specialized extensions of a neuron that receive signals from other neurons or sensory cells, acting as the primary input region.

Question 3

Ramesh Sharma borrows Rs. 8,000 for 3 years at 5% p.a. simple interest. He lends it to Manohar at 7% p.a. for 3 years. Find his gain.

Accepted Answer

Ramesh's gain is the difference in interest rates applied to the principal. Calculate the interest difference (7%-5%=2%) on Rs. 8000 for 3 years: (8000 * 2 * 3) / 100 = Rs. 480.

Question 4

Who is regarded as the Father of the Indian Nuclear Program?

Accepted Answer

Dr. Homi J. Bhabha is widely recognized as the Father of the Indian Nuclear Program for his pioneering efforts and vision in establishing India's nuclear capabilities.

Question 5

In Excel, what shortcut key is used to fill the selected cell with active cells to the right?

Accepted Answer

To fill the selected cell(s) to the right with the content of the active cell, the shortcut key is Ctrl + R. This is a direct Excel function.

Question 6

If5‌tan‌α=4, then find the value of‌5sin‌α−3‌cos‌α5sin‌α+2‌cos‌α

Accepted Answer

Given 5tanα = 4, so tanα = 4/5. Divide numerator and denominator of the expression by cosα. Substitute tanα = 4/5 to get (5(4/5) - 3) / (5(4/5) + 2) = (4-3)/(4+2) = 1/6.

Question 7

The number whose only factors are 1 and the number itself is called a/an ________ number.

Accepted Answer

A prime number is defined as a natural number greater than 1 that has no positive divisors other than 1 and itself. This directly matches the definition given.

Question 8

A, B and C can complete a piece of work in 10 days, 15 days and 20 days respectively. If they work together, then the work will be completed in:

Accepted Answer

Calculate individual work rates (1/10, 1/15, 1/20). Sum them to find combined rate (13/60). The total time is the reciprocal of the combined rate, 60/13 days, which is 4 8/13 days.

Question 9

If A + B = 90° and sin A =‌35, then the value of tan B is:

Accepted Answer

Given A + B = 90°, so B = 90° - A. Thus, tan B = tan(90° - A) = cot A. Since sin A = 3/5, cos A = 4/5. Therefore, cot A = cos A / sin A = (4/5) / (3/5) = 4/3.

Question 10

The first national flag of India is said to have hoisted at _______ in 1906.

Accepted Answer

The first national flag of India was hoisted on August 7, 1906, at Parsee Bagan Square (now Gireesh Park) in Kolkata, during the Swadeshi movement.

Question 11

Who has won the Nine Dots Prize Award 2019?

Accepted Answer

Annie Zaidi, an Indian writer, won the Nine Dots Prize Award in 2019 for her essay 'Bread, Cement, Cactus'. This prize is awarded for original thinking on contemporary issues.

Question 12

The value of sin(45° + A) - cos (45° - A) is:

Accepted Answer

Use the identity cos(90° - θ) = sin(θ). Here, cos(45° - A) = cos(90° - (45° + A)) = sin(45° + A). Thus, the expression becomes sin(45° + A) - sin(45° + A) = 0.

Question 13

A train covers 400 km at a uniform speed. If the speed had been 10 km/h more, it would have taken 2 h less for the same journey. Find the speed of the train.

Accepted Answer

Let speed be 's'. Time = 400/s. New speed = s+10. New time = 400/(s+10). Given 400/s - 400/(s+10) = 2. Solving this quadratic equation gives s = 40 km/h.

Question 14

Simplify‌11.2.3+‌12.3.4+‌13.4.5+‌14.5.6

Accepted Answer

Each term 1/(n(n+1)(n+2)) can be written as 1/2 * [1/(n(n+1)) - 1/((n+1)(n+2))]. Summing these terms creates a telescoping series, simplifying to 1/2 * [1/(1*2) - 1/(5*6)] = 1/2 * [1/2 - 1/30] = 1/2 * [14/30] = 7/30.

Question 15

If (3x + 2y) : (3x – 2y) = 5 : 3 then find x : y.

Accepted Answer

Apply componendo and dividendo rule: (A+B)/(A-B) = (C+D)/(C-D). This simplifies the ratio to 3x/2y = (5+3)/(5-3) = 8/2 = 4. Thus, x/y = 4 * (2/3) = 8/3.

Question 16

If tan θ =x−‌14x, then sec θ - tan θ is equal to:

Accepted Answer

Use sec²θ - tan²θ = 1, so sec θ = ±√(1 + tan²θ). Substitute tan θ, simplify to get sec θ = ±(x + 1/(4x)). Then calculate sec θ - tan θ for both positive and negative sec θ values.

Question 17

​(√3+√11)2is a/an:

Accepted Answer

Expand (√3+√11)² as (√3)² + (√11)² + 2(√3)(√11) = 3 + 11 + 2√33 = 14 + 2√33. Since √33 is irrational, 14 + 2√33 is also irrational.

Question 18

The pistil in the flower is _______.

Accepted Answer

The pistil is the female reproductive organ of a flower, comprising the stigma, style, and ovary, essential for seed production.

Question 19

Find the sum of the numbers between 400 and 500 such that when 8, 12, and 16 divide them, it leaves 5 as remainder in each case.

Accepted Answer

Find the LCM of 8, 12, 16, which is 48. Numbers are of the form 48k + 5. Between 400 and 500, these are 48*9 + 5 = 437 and 48*10 + 5 = 485. Their sum is 437 + 485 = 922.

Question 20

Which of these is NOT a computer characteristic?

Accepted Answer

Computers possess speed, accuracy, and data storage capabilities. Intelligence quotient (IQ) is a human characteristic, not a computer's inherent trait.