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Finding the Fourth Proportional to 1,390.57, 2,085.19 and 512.78

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Solution

The fourth proportional to 1,390.57, 2,085.19 and 512.78 is: 768.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.57 : 2,085.19 = 512.78 : x
  2. Step 2: Convert to fraction form
    1,390.57/2,085.19 = 512.78/x
  3. Step 3: Cross multiply
    1,390.57x = 2,085.19 × 512.78
  4. Step 4: Simplify right side
    1,390.57x = 1,069,246.63
  5. Step 5: Solve for x
    x = 1,069,246.63/1,390.57
  6. Step 6: Final answer
    x = 768.93

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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.