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Finding the Fourth Proportional to 810.15, 1,214.82 and 420.09

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Solution

The fourth proportional to 810.15, 1,214.82 and 420.09 is: 629.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.15 : 1,214.82 = 420.09 : x
  2. Step 2: Convert to fraction form
    810.15/1,214.82 = 420.09/x
  3. Step 3: Cross multiply
    810.15x = 1,214.82 × 420.09
  4. Step 4: Simplify right side
    810.15x = 510,333.73
  5. Step 5: Solve for x
    x = 510,333.73/810.15
  6. Step 6: Final answer
    x = 629.92

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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.