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Finding the Fourth Proportional to 687.78, 949.14 and 393.06

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Solution

The fourth proportional to 687.78, 949.14 and 393.06 is: 542.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.78 : 949.14 = 393.06 : x
  2. Step 2: Convert to fraction form
    687.78/949.14 = 393.06/x
  3. Step 3: Cross multiply
    687.78x = 949.14 × 393.06
  4. Step 4: Simplify right side
    687.78x = 373,068.97
  5. Step 5: Solve for x
    x = 373,068.97/687.78
  6. Step 6: Final answer
    x = 542.42

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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.