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Finding the Fourth Proportional to 1,385.68, 2,078.76 and 521.20

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Solution

The fourth proportional to 1,385.68, 2,078.76 and 521.20 is: 781.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,385.68 : 2,078.76 = 521.20 : x
  2. Step 2: Convert to fraction form
    1,385.68/2,078.76 = 521.20/x
  3. Step 3: Cross multiply
    1,385.68x = 2,078.76 × 521.20
  4. Step 4: Simplify right side
    1,385.68x = 1,083,449.71
  5. Step 5: Solve for x
    x = 1,083,449.71/1,385.68
  6. Step 6: Final answer
    x = 781.89

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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.