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Finding the Fourth Proportional to 686.75, 947.68 and 388

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Solution

The fourth proportional to 686.75, 947.68 and 388 is: 535.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.75 : 947.68 = 388 : x
  2. Step 2: Convert to fraction form
    686.75/947.68 = 388/x
  3. Step 3: Cross multiply
    686.75x = 947.68 × 388
  4. Step 4: Simplify right side
    686.75x = 367,699.84
  5. Step 5: Solve for x
    x = 367,699.84/686.75
  6. Step 6: Final answer
    x = 535.42

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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.