RRB NTPC 2021 PYQs

Question 1

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 2

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 3

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 4

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 5

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 6

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 7

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 8

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 9

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 10

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 11

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 12

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 13

​(√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 14

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 15

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 16

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.

Question 17

Nobel Laureate, Kailash Satyarthi is associated with which of the following organization?

Accepted Answer

Kailash Satyarthi, a Nobel Peace Prize laureate, is widely recognized for his work with the Bachpan Bachao Andolan, an organization dedicated to child rights.

Question 18

With which Chinese technology company has the Trump Administration banned the US government agencies from doing business?

Accepted Answer

The Trump administration banned US government agencies from doing business with Huawei due to national security concerns, a widely reported event.

Question 19

According to the Constitution of India, the minimum age requirement for being a member of Panchayat is ________.

Accepted Answer

Article 243F of the Indian Constitution specifies that the minimum age for a person to be chosen as a member of a Panchayat is 21 years.

Question 20

If a man sold 20 books for Rs. 1800, gaining there by the cost price of 5 books, then find the cost price of a book.

Accepted Answer

Let CP of one book be x. Total CP of 20 books = 20x. Profit = 5x. SP = CP + Profit. So, 1800 = 20x + 5x = 25x. Thus, x = 1800/25 = 72.