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Finding the Fourth Proportional to 921.40, 1,380.36 and 509.92

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Solution

The fourth proportional to 921.40, 1,380.36 and 509.92 is: 763.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.40 : 1,380.36 = 509.92 : x
  2. Step 2: Convert to fraction form
    921.40/1,380.36 = 509.92/x
  3. Step 3: Cross multiply
    921.40x = 1,380.36 × 509.92
  4. Step 4: Simplify right side
    921.40x = 703,873.17
  5. Step 5: Solve for x
    x = 703,873.17/921.40
  6. Step 6: Final answer
    x = 763.92

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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.