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Finding the Fourth Proportional to 938.31, 1,406.70 and 390.89

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Solution

The fourth proportional to 938.31, 1,406.70 and 390.89 is: 586.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.31 : 1,406.70 = 390.89 : x
  2. Step 2: Convert to fraction form
    938.31/1,406.70 = 390.89/x
  3. Step 3: Cross multiply
    938.31x = 1,406.70 × 390.89
  4. Step 4: Simplify right side
    938.31x = 549,868.48
  5. Step 5: Solve for x
    x = 549,868.48/938.31
  6. Step 6: Final answer
    x = 586.02

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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.