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Finding the Fourth Proportional to 689.12, 1,038.52 and 620.72

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Solution

The fourth proportional to 689.12, 1,038.52 and 620.72 is: 935.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.12 : 1,038.52 = 620.72 : x
  2. Step 2: Convert to fraction form
    689.12/1,038.52 = 620.72/x
  3. Step 3: Cross multiply
    689.12x = 1,038.52 × 620.72
  4. Step 4: Simplify right side
    689.12x = 644,630.13
  5. Step 5: Solve for x
    x = 644,630.13/689.12
  6. Step 6: Final answer
    x = 935.44

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.