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Finding the Fourth Proportional to 693.70, 1,040.55 and 640.90

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Solution

The fourth proportional to 693.70, 1,040.55 and 640.90 is: 961.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    693.70 : 1,040.55 = 640.90 : x
  2. Step 2: Convert to fraction form
    693.70/1,040.55 = 640.90/x
  3. Step 3: Cross multiply
    693.70x = 1,040.55 × 640.90
  4. Step 4: Simplify right side
    693.70x = 666,888.50
  5. Step 5: Solve for x
    x = 666,888.50/693.70
  6. Step 6: Final answer
    x = 961.35

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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.