The simple interest on a sum of money for 12 years is Rs 3756. If the principal becomes 4 times in next 6 years, then what will be the total interest (in Rs) obtained for 24 years? 12 वर्षों के लिए धनराशि पर साधारण ब्याज 3756 रु है। यदि मूलधन अगले 6 वर्षों में 4 गुना हो जाता है, तो 24 वर्षों के लिए प्राप्त कुल ब्याज (रु में) क्या होगा?

SI for 12 years = Rs 3756, so SI per year = Rs 313.50. Principal becomes 4 times in next 6 years means interest for 6 years = 3P (from P to 4P). So 3P = 6 × 313.50 = 1881, giving P = 627. Total interest for 24 years = 2 × 3756 + 1881 = 9393. However, solving directly: SI for 12 years = 3756, SI for 24 years = 7512 (double). The 'principal becomes 4 times' information is used to find the rate.