Multiple choice

An amount is invested 6% simple interest and another amount double the first one at 10% simple interest. The total interest per annum earned is Rs. 1170. What will be the total interest if the entire amount is invested at 10% एक धनराशि को 6% साधारण ब्याज पर निवेश किया गया और दूसरी धनराशि जोकि पहली का दोगुना है, को 10% साधारण ब्याज पर निवेश किया। प्रतिवर्ष प्राप्त कुल ब्याज 1170 रू. है। कुल ब्याज क्या होगा यदि पूरी धनराशि को 10% पर निवेशित किया जाता है।

  1. Rs.1350

  2. Rs.13500

  3. Rs.4500

  4. Rs. 9000

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A Correct answer
Explanation

Let first amount = x at 6% SI, second amount = 2x at 10% SI. Total interest per year = x*0.06 + 2x*0.10 = 0.06x + 0.20x = 0.26x = 1170. Therefore, x = 1170/0.26 = 4500. Total amount = x + 2x = 3x = 13500. If entire amount invested at 10%: Interest = 13500 * 0.10 = 1350. Option B (13500) is the total principal, not interest. Option C (4500) is just the first investment. Option D (9000) is 2x, not the interest.