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Finding the Fourth Proportional to 678.95, 1,019.78 and 405.57

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Solution

The fourth proportional to 678.95, 1,019.78 and 405.57 is: 609.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.95 : 1,019.78 = 405.57 : x
  2. Step 2: Convert to fraction form
    678.95/1,019.78 = 405.57/x
  3. Step 3: Cross multiply
    678.95x = 1,019.78 × 405.57
  4. Step 4: Simplify right side
    678.95x = 413,595.49
  5. Step 5: Solve for x
    x = 413,595.49/678.95
  6. Step 6: Final answer
    x = 609.17

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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.