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Finding the Fourth Proportional to 938.30, 1,407.86 and 390.61

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Solution

The fourth proportional to 938.30, 1,407.86 and 390.61 is: 586.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.30 : 1,407.86 = 390.61 : x
  2. Step 2: Convert to fraction form
    938.30/1,407.86 = 390.61/x
  3. Step 3: Cross multiply
    938.30x = 1,407.86 × 390.61
  4. Step 4: Simplify right side
    938.30x = 549,924.19
  5. Step 5: Solve for x
    x = 549,924.19/938.30
  6. Step 6: Final answer
    x = 586.09

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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.