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Finding the Fourth Proportional to 938.41, 1,407.31 and 390.31

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Solution

The fourth proportional to 938.41, 1,407.31 and 390.31 is: 585.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.41 : 1,407.31 = 390.31 : x
  2. Step 2: Convert to fraction form
    938.41/1,407.31 = 390.31/x
  3. Step 3: Cross multiply
    938.41x = 1,407.31 × 390.31
  4. Step 4: Simplify right side
    938.41x = 549,282.67
  5. Step 5: Solve for x
    x = 549,282.67/938.41
  6. Step 6: Final answer
    x = 585.33

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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.