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Finding the Fourth Proportional to 810.21, 1,215.17 and 399.09

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Solution

The fourth proportional to 810.21, 1,215.17 and 399.09 is: 598.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.21 : 1,215.17 = 399.09 : x
  2. Step 2: Convert to fraction form
    810.21/1,215.17 = 399.09/x
  3. Step 3: Cross multiply
    810.21x = 1,215.17 × 399.09
  4. Step 4: Simplify right side
    810.21x = 484,960.20
  5. Step 5: Solve for x
    x = 484,960.20/810.21
  6. Step 6: Final answer
    x = 598.56

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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.