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Finding the Fourth Proportional to 805.12, 1,207.68 and 643.12

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Solution

The fourth proportional to 805.12, 1,207.68 and 643.12 is: 964.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    805.12 : 1,207.68 = 643.12 : x
  2. Step 2: Convert to fraction form
    805.12/1,207.68 = 643.12/x
  3. Step 3: Cross multiply
    805.12x = 1,207.68 × 643.12
  4. Step 4: Simplify right side
    805.12x = 776,683.16
  5. Step 5: Solve for x
    x = 776,683.16/805.12
  6. Step 6: Final answer
    x = 964.68

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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.