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Finding the Fourth Proportional to 810.47, 1,215.34 and 399.13

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Solution

The fourth proportional to 810.47, 1,215.34 and 399.13 is: 598.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.47 : 1,215.34 = 399.13 : x
  2. Step 2: Convert to fraction form
    810.47/1,215.34 = 399.13/x
  3. Step 3: Cross multiply
    810.47x = 1,215.34 × 399.13
  4. Step 4: Simplify right side
    810.47x = 485,078.65
  5. Step 5: Solve for x
    x = 485,078.65/810.47
  6. Step 6: Final answer
    x = 598.52

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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.