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Finding the Fourth Proportional to 810, 1,215.81 and 425.25

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Solution

The fourth proportional to 810, 1,215.81 and 425.25 is: 638.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    810 : 1,215.81 = 425.25 : x
  2. Step 2: Convert to fraction form
    810/1,215.81 = 425.25/x
  3. Step 3: Cross multiply
    810x = 1,215.81 × 425.25
  4. Step 4: Simplify right side
    810x = 517,023.20
  5. Step 5: Solve for x
    x = 517,023.20/810
  6. Step 6: Final answer
    x = 638.30

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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.