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Finding the Fourth Proportional to 387.78, 534.60 and 309.36

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Solution

The fourth proportional to 387.78, 534.60 and 309.36 is: 426.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    387.78 : 534.60 = 309.36 : x
  2. Step 2: Convert to fraction form
    387.78/534.60 = 309.36/x
  3. Step 3: Cross multiply
    387.78x = 534.60 × 309.36
  4. Step 4: Simplify right side
    387.78x = 165,383.86
  5. Step 5: Solve for x
    x = 165,383.86/387.78
  6. Step 6: Final answer
    x = 426.49

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.