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Finding the Fourth Proportional to 520.90, 781.20 and 191.80

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Solution

The fourth proportional to 520.90, 781.20 and 191.80 is: 287.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    520.90 : 781.20 = 191.80 : x
  2. Step 2: Convert to fraction form
    520.90/781.20 = 191.80/x
  3. Step 3: Cross multiply
    520.90x = 781.20 × 191.80
  4. Step 4: Simplify right side
    520.90x = 149,834.16
  5. Step 5: Solve for x
    x = 149,834.16/520.90
  6. Step 6: Final answer
    x = 287.64

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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.