Maths : Basic Numeracy

Q 136 / 370

UPSC CSE Prelims 2022

A bill for ₹ 1,840 is paid in the denominations of ₹50, ₹20 and ₹10 notes. 50 notes in all are used. Consider the following statements:

  1. 25 notes of ₹50 are used and the remaining are in the denominations of ₹20 and ₹10.
  2. 35 notes of ₹20 are used and the remaining are in the denominations of ₹50 and ₹10.
  3. 20 notes of ₹10 are used and the remaining are in the denominations of ₹50 and ₹20.

Which of the above statements are not correct?

EXPLANATION

Correct Option

Statements 1, 2, and 3 are all incorrect.

Incorrect Options

The problem states a total bill of ₹ 1,840 is paid using 50 notes in denominations of ₹50, ₹20, and ₹10. Each statement is evaluated for its consistency with these conditions.

Statement 1 Analysis:

  • If 25 notes of ₹50 are used, the value contributed is 25 × 50 = ₹ 1,250.
  • The remaining amount required is 1840 - 1250 = ₹ 590.
  • The remaining number of notes is 50 - 25 = 25 notes.
  • These 25 notes must be in ₹20 and ₹10 denominations. The maximum value obtainable from 25 notes of ₹20 and ₹10 occurs if all 25 notes are ₹20, yielding 25 × 20 = ₹ 500.
  • Since ₹590 is needed but only a maximum of ₹500 can be generated from the remaining notes, Statement 1 is incorrect.

Statement 2 Analysis:

  • If 35 notes of ₹20 are used, the value contributed is 35 × 20 = ₹ 700.
  • The remaining amount required is 1840 - 700 = ₹ 1,140.
  • The remaining number of notes is 50 - 35 = 15 notes.
  • These 15 notes must be in ₹50 and ₹10 denominations. The maximum value obtainable from 15 notes of ₹50 and ₹10 occurs if all 15 notes are ₹50, yielding 15 × 50 = ₹ 750.
  • Since ₹1,140 is needed but only a maximum of ₹750 can be generated from the remaining notes, Statement 2 is incorrect.

Statement 3 Analysis:

  • If 20 notes of ₹10 are used, the value contributed is 20 × 10 = ₹ 200.
  • The remaining amount required is 1840 - 200 = ₹ 1,640.
  • The remaining number of notes is 50 - 20 = 30 notes.
  • These 30 notes must be in ₹50 and ₹20 denominations. The maximum value obtainable from 30 notes of ₹50 and ₹20 occurs if all 30 notes are ₹50, yielding 30 × 50 = ₹ 1,500.
  • Since ₹1,640 is needed but only a maximum of ₹1,500 can be generated from the remaining notes, Statement 3 is incorrect.

As all three statements (1, 2, and 3) are found to be inconsistent with the given conditions, they are all not correct. Therefore, the option indicating that statements 1, 2, and 3 are not correct is the appropriate answer.