Selection Post Phase XIV (Graduate)22 Sep 2026Shift 1Simple Interest

The ratio of the principal and the amount after 5 years is 4 : 7. In how many years will the ratio of the principal and the simple interest become 5 : 6 at the same rate?
मूलधन (Principal) और 5 वर्षों के बाद के मिश्रधन (Amount) का अनुपात (Ratio) 4 : 7 है। उसी दर पर कितने वर्षों में मूलधन और साधारण ब्याज (Simple interest) का अनुपात 5 : 6 हो जाएगा?

Answer और ExplanationAnswer and explanation

Answer: (A) 8 years

माना मूलधन (Principal) P = 4k, मिश्रधन (Amount) A = 7k ⇒ 5 वर्ष का SI = 3k

SI = P का 34 = P का 75%, 5 वर्ष में ⇒ R = 755 = 15%

अब P : SI = 5 : 6 ⇒ SI = P का 65 = P का 120%

T = 12015 = 8 वर्ष

✓

इसमें 8 वर्ष लगेंगे।

Let P = 4k, A = 7k ⇒ SI in 5 years = 3k

SI = 34 of P = 75% of P in 5 years ⇒ R = 755 = 15%

Now P : SI = 5 : 6 ⇒ SI = 65 of P = 120% of P

T = 12015 = 8 years

✓

It will take 8 years.

SMART APPROACH

RT = कुल प्रतिशत। पहली स्थिति में T = 5 पर RT = 75, दूसरी में उसी R पर RT = 120, तो T = 5 × 12075 = 8 वर्ष।

RT = total percent. First case: RT = 75 with T = 5. Second case: RT = 120 with the same R, so T = 5 × 12075 = 8 years.

Source: Selection Post Phase XIV (Graduate) · 22 Sep 2026 · Shift 1। Solution: Prashant Sir, Vijayastra।Source: Selection Post Phase XIV (Graduate) · 22 Sep 2026 · Shift 1. Solution by Prashant Sir, from Vijayastra.