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Finding the Fourth Proportional to 938.22, 1,406.57 and 390.81

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Solution

The fourth proportional to 938.22, 1,406.57 and 390.81 is: 585.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.22 : 1,406.57 = 390.81 : x
  2. Step 2: Convert to fraction form
    938.22/1,406.57 = 390.81/x
  3. Step 3: Cross multiply
    938.22x = 1,406.57 × 390.81
  4. Step 4: Simplify right side
    938.22x = 549,699.67
  5. Step 5: Solve for x
    x = 549,699.67/938.22
  6. Step 6: Final answer
    x = 585.90

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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.