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Finding the Fourth Proportional to 621.86, 857.91 and 400.78

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Solution

The fourth proportional to 621.86, 857.91 and 400.78 is: 552.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    621.86 : 857.91 = 400.78 : x
  2. Step 2: Convert to fraction form
    621.86/857.91 = 400.78/x
  3. Step 3: Cross multiply
    621.86x = 857.91 × 400.78
  4. Step 4: Simplify right side
    621.86x = 343,833.17
  5. Step 5: Solve for x
    x = 343,833.17/621.86
  6. Step 6: Final answer
    x = 552.91

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.