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Finding the Fourth Proportional to 731, 1,008.78 and 420.50

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Solution

The fourth proportional to 731, 1,008.78 and 420.50 is: 580.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    731 : 1,008.78 = 420.50 : x
  2. Step 2: Convert to fraction form
    731/1,008.78 = 420.50/x
  3. Step 3: Cross multiply
    731x = 1,008.78 × 420.50
  4. Step 4: Simplify right side
    731x = 424,191.99
  5. Step 5: Solve for x
    x = 424,191.99/731
  6. Step 6: Final answer
    x = 580.29

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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.