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Finding the Fourth Proportional to 938.72, 1,407.71 and 280.40

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Solution

The fourth proportional to 938.72, 1,407.71 and 280.40 is: 420.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.72 : 1,407.71 = 280.40 : x
  2. Step 2: Convert to fraction form
    938.72/1,407.71 = 280.40/x
  3. Step 3: Cross multiply
    938.72x = 1,407.71 × 280.40
  4. Step 4: Simplify right side
    938.72x = 394,715.55
  5. Step 5: Solve for x
    x = 394,715.55/938.72
  6. Step 6: Final answer
    x = 420.48

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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.