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Finding the Fourth Proportional to 1,239.10, 1,855 and 915.91

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Solution

The fourth proportional to 1,239.10, 1,855 and 915.91 is: 1,371.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,239.10 : 1,855 = 915.91 : x
  2. Step 2: Convert to fraction form
    1,239.10/1,855 = 915.91/x
  3. Step 3: Cross multiply
    1,239.10x = 1,855 × 915.91
  4. Step 4: Simplify right side
    1,239.10x = 1,699,013.05
  5. Step 5: Solve for x
    x = 1,699,013.05/1,239.10
  6. Step 6: Final answer
    x = 1,371.17

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.