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Finding the Fourth Proportional to 515.70, 711.50 and 305.78

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Solution

The fourth proportional to 515.70, 711.50 and 305.78 is: 421.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    515.70 : 711.50 = 305.78 : x
  2. Step 2: Convert to fraction form
    515.70/711.50 = 305.78/x
  3. Step 3: Cross multiply
    515.70x = 711.50 × 305.78
  4. Step 4: Simplify right side
    515.70x = 217,557.38
  5. Step 5: Solve for x
    x = 217,557.38/515.70
  6. Step 6: Final answer
    x = 421.87

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.