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Finding the Fourth Proportional to 1,318.75, 1,978.14 and 406.75

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Solution

The fourth proportional to 1,318.75, 1,978.14 and 406.75 is: 610.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,318.75 : 1,978.14 = 406.75 : x
  2. Step 2: Convert to fraction form
    1,318.75/1,978.14 = 406.75/x
  3. Step 3: Cross multiply
    1,318.75x = 1,978.14 × 406.75
  4. Step 4: Simplify right side
    1,318.75x = 804,608.45
  5. Step 5: Solve for x
    x = 804,608.45/1,318.75
  6. Step 6: Final answer
    x = 610.13

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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.