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Finding the Fourth Proportional to 689.78, 1,034.67 and 647.54

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Solution

The fourth proportional to 689.78, 1,034.67 and 647.54 is: 971.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.78 : 1,034.67 = 647.54 : x
  2. Step 2: Convert to fraction form
    689.78/1,034.67 = 647.54/x
  3. Step 3: Cross multiply
    689.78x = 1,034.67 × 647.54
  4. Step 4: Simplify right side
    689.78x = 669,990.21
  5. Step 5: Solve for x
    x = 669,990.21/689.78
  6. Step 6: Final answer
    x = 971.31

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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.