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Finding the Fourth Proportional to 753.12, 1,129.68 and 428.32

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Solution

The fourth proportional to 753.12, 1,129.68 and 428.32 is: 642.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    753.12 : 1,129.68 = 428.32 : x
  2. Step 2: Convert to fraction form
    753.12/1,129.68 = 428.32/x
  3. Step 3: Cross multiply
    753.12x = 1,129.68 × 428.32
  4. Step 4: Simplify right side
    753.12x = 483,864.54
  5. Step 5: Solve for x
    x = 483,864.54/753.12
  6. Step 6: Final answer
    x = 642.48

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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.