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Finding the Fourth Proportional to 805.12, 1,207.68 and 642.60

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Solution

The fourth proportional to 805.12, 1,207.68 and 642.60 is: 963.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    805.12 : 1,207.68 = 642.60 : x
  2. Step 2: Convert to fraction form
    805.12/1,207.68 = 642.60/x
  3. Step 3: Cross multiply
    805.12x = 1,207.68 × 642.60
  4. Step 4: Simplify right side
    805.12x = 776,055.17
  5. Step 5: Solve for x
    x = 776,055.17/805.12
  6. Step 6: Final answer
    x = 963.90

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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.