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Finding the Fourth Proportional to 938.64, 1,407.87 and 390.66

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Solution

The fourth proportional to 938.64, 1,407.87 and 390.66 is: 585.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.64 : 1,407.87 = 390.66 : x
  2. Step 2: Convert to fraction form
    938.64/1,407.87 = 390.66/x
  3. Step 3: Cross multiply
    938.64x = 1,407.87 × 390.66
  4. Step 4: Simplify right side
    938.64x = 549,998.49
  5. Step 5: Solve for x
    x = 549,998.49/938.64
  6. Step 6: Final answer
    x = 585.95

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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.