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Finding the Fourth Proportional to 805.20, 1,207.85 and 257.40

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Solution

The fourth proportional to 805.20, 1,207.85 and 257.40 is: 386.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    805.20 : 1,207.85 = 257.40 : x
  2. Step 2: Convert to fraction form
    805.20/1,207.85 = 257.40/x
  3. Step 3: Cross multiply
    805.20x = 1,207.85 × 257.40
  4. Step 4: Simplify right side
    805.20x = 310,899.30
  5. Step 5: Solve for x
    x = 310,899.30/805.20
  6. Step 6: Final answer
    x = 386.12

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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.