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Finding the Fourth Proportional to 921.21, 1,379.43 and 509.86

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Solution

The fourth proportional to 921.21, 1,379.43 and 509.86 is: 763.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.21 : 1,379.43 = 509.86 : x
  2. Step 2: Convert to fraction form
    921.21/1,379.43 = 509.86/x
  3. Step 3: Cross multiply
    921.21x = 1,379.43 × 509.86
  4. Step 4: Simplify right side
    921.21x = 703,317.90
  5. Step 5: Solve for x
    x = 703,317.90/921.21
  6. Step 6: Final answer
    x = 763.47

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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.