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Finding the Fourth Proportional to 672.50, 1,009.20 and 287.78

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Solution

The fourth proportional to 672.50, 1,009.20 and 287.78 is: 431.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    672.50 : 1,009.20 = 287.78 : x
  2. Step 2: Convert to fraction form
    672.50/1,009.20 = 287.78/x
  3. Step 3: Cross multiply
    672.50x = 1,009.20 × 287.78
  4. Step 4: Simplify right side
    672.50x = 290,427.58
  5. Step 5: Solve for x
    x = 290,427.58/672.50
  6. Step 6: Final answer
    x = 431.86

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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.