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Finding the Fourth Proportional to 753.18, 1,039.31 and 421.55

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Solution

The fourth proportional to 753.18, 1,039.31 and 421.55 is: 581.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    753.18 : 1,039.31 = 421.55 : x
  2. Step 2: Convert to fraction form
    753.18/1,039.31 = 421.55/x
  3. Step 3: Cross multiply
    753.18x = 1,039.31 × 421.55
  4. Step 4: Simplify right side
    753.18x = 438,127.52
  5. Step 5: Solve for x
    x = 438,127.52/753.18
  6. Step 6: Final answer
    x = 581.70

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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.