Maths : Basic Numeracy

Q 214 / 370

UPSC CSE Prelims 2020

Let p, q, r and s be natural numbers such that
p−2016=q+2017=r−2018=s+2019
Which one of the following is the largest natural number?

EXPLANATION

Correct Option (3)

Let the common value of the given expression be k.
p−2016=q+2017=r−2018=s+2019=k
From this, each variable can be expressed in terms of k:

  • p=k+2016
  • q=k−2017
  • r=k+2018
  • s=k−2019

To identify the largest natural number, we compare the constant terms associated with k. The constants are +2016, −2017, +2018, and −2019. The largest among these constants is +2018. Consequently, r=k+2018 represents the largest natural number.

Incorrect Options:

Based on the expressions derived:

  • p=k+2016
  • q=k−2017
  • s=k−2019

Comparing these with r=k+2018:

  • Since 2016 < 2018, p is less than r.
  • Since -2017 < 2018, q is less than r.
  • Since -2019 < 2018, s is less than r.

The complete order from smallest to largest is s < q < p < r. Therefore, p,q, and s are not the largest natural numbers.