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Finding the Fourth Proportional to 672.90, 1,007.92 and 428.68

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Solution

The fourth proportional to 672.90, 1,007.92 and 428.68 is: 642.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    672.90 : 1,007.92 = 428.68 : x
  2. Step 2: Convert to fraction form
    672.90/1,007.92 = 428.68/x
  3. Step 3: Cross multiply
    672.90x = 1,007.92 × 428.68
  4. Step 4: Simplify right side
    672.90x = 432,075.15
  5. Step 5: Solve for x
    x = 432,075.15/672.90
  6. Step 6: Final answer
    x = 642.11

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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.