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Finding the Fourth Proportional to 689.50, 1,029.26 and 643.40

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Solution

The fourth proportional to 689.50, 1,029.26 and 643.40 is: 960.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.50 : 1,029.26 = 643.40 : x
  2. Step 2: Convert to fraction form
    689.50/1,029.26 = 643.40/x
  3. Step 3: Cross multiply
    689.50x = 1,029.26 × 643.40
  4. Step 4: Simplify right side
    689.50x = 662,225.88
  5. Step 5: Solve for x
    x = 662,225.88/689.50
  6. Step 6: Final answer
    x = 960.44

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.