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Finding the Fourth Proportional to 805.76, 1,207.37 and 643.40

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Solution

The fourth proportional to 805.76, 1,207.37 and 643.40 is: 964.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    805.76 : 1,207.37 = 643.40 : x
  2. Step 2: Convert to fraction form
    805.76/1,207.37 = 643.40/x
  3. Step 3: Cross multiply
    805.76x = 1,207.37 × 643.40
  4. Step 4: Simplify right side
    805.76x = 776,821.86
  5. Step 5: Solve for x
    x = 776,821.86/805.76
  6. Step 6: Final answer
    x = 964.09

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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.