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Finding the Fourth Proportional to 810.78, 1,215.56 and 400.12

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Solution

The fourth proportional to 810.78, 1,215.56 and 400.12 is: 599.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.78 : 1,215.56 = 400.12 : x
  2. Step 2: Convert to fraction form
    810.78/1,215.56 = 400.12/x
  3. Step 3: Cross multiply
    810.78x = 1,215.56 × 400.12
  4. Step 4: Simplify right side
    810.78x = 486,369.87
  5. Step 5: Solve for x
    x = 486,369.87/810.78
  6. Step 6: Final answer
    x = 599.88

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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.