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Finding the Fourth Proportional to 667.47, 921.30 and 387.78

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Solution

The fourth proportional to 667.47, 921.30 and 387.78 is: 535.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.47 : 921.30 = 387.78 : x
  2. Step 2: Convert to fraction form
    667.47/921.30 = 387.78/x
  3. Step 3: Cross multiply
    667.47x = 921.30 × 387.78
  4. Step 4: Simplify right side
    667.47x = 357,261.71
  5. Step 5: Solve for x
    x = 357,261.71/667.47
  6. Step 6: Final answer
    x = 535.25

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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.