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Finding the Fourth Proportional to 643.95, 888.30 and 381.78

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Solution

The fourth proportional to 643.95, 888.30 and 381.78 is: 526.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.95 : 888.30 = 381.78 : x
  2. Step 2: Convert to fraction form
    643.95/888.30 = 381.78/x
  3. Step 3: Cross multiply
    643.95x = 888.30 × 381.78
  4. Step 4: Simplify right side
    643.95x = 339,135.17
  5. Step 5: Solve for x
    x = 339,135.17/643.95
  6. Step 6: Final answer
    x = 526.65

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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.