Question
Download Solution PDFWhich two signs should be interchanged to make the given equation correct?
(72 ÷ 18) + 30 × 8 - 4 = 20
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFGiven : (72 ÷ 18) + 30 × 8 - 4 = 20
According to the question, after interchanging the numbers :
Option 1) + and -
(72 ÷ 18) + 30 × 8 - 4 = 20 ⇒ (72 ÷ 18) - 30 × 8 + 4 = 20
⇒ (72 ÷ 18) - 30 × 8 + 4 = 20
⇒ 4 - 30 × 8 + 4 = 20
⇒ 4 + 4 - 240 = 20
⇒ 8 - 240 = 20
⇒ -232 ≠ 20 (LHS ≠ RHS)
Option 2) + and ×
(72 ÷ 18) + 30 × 8 - 4 = 20 ⇒ (72 ÷ 18) × 30 + 8 - 4 = 20
⇒ (72 ÷ 18) × 30 + 8 - 4 = 20
⇒ 4 × 30 + 8 - 4 = 20
⇒ 120 + 8 - 4 = 20
⇒ 128 - 4 = 20
⇒124 ≠ 20 (LHS ≠ RHS)
Option 3) × and ÷
(72 ÷ 18) + 30 × 8 - 4 = 20 ⇒ (72 × 18) + 30 ÷ 8 - 4 = 20
⇒ (72 × 18) + 30 ÷ 8 - 4 = 20
⇒ 1296 + 30 ÷ 8 - 4 = 20
⇒ 1296 + 3.75 - 4 = 20
⇒ 1299.75 - 4 = 20
⇒ 1295.75 ≠ 20 (LHS ≠ RHS)
Option 4) + and ÷
(72 ÷ 18) + 30 × 8 - 4 = 20 ⇒ (72 + 18) ÷ 30 × 8 - 4 = 20
⇒ (72 + 18) ÷ 30 × 8 - 4 = 20
⇒ 90 ÷ 30 × 8 - 4 = 20
⇒ 3 × 8 - 4 = 20
⇒ 24 - 4 = 20
⇒ 20 = 20 (LHS = RHS)
Hence, "Option 4" is the correct answer.
Last updated on Jun 24, 2025
-> The CSIR Junior Secretariat Assistant 2025 has been released for 9 vacancies.
-> Candidates can apply online from 17th June to 7th July 2025.
-> The CSIR JSA salary ranges from INR 19,900 - INR 63,200 (Indian Institute of Petroleum, Dehradun & Institute of Microbial Technology) and INR 35,600 (Indian Institute of Toxicology Research).
-> The selection of candidates for this post will be based on a Written Exam, followed by a Computer Typing Test.
-> Prepare for the exam with CSIR Junior Secretariat Assistant Previous Year Papers.