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Finding the Fourth Proportional to 1,287.78, 1,928.07 and 670.14

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Solution

The fourth proportional to 1,287.78, 1,928.07 and 670.14 is: 1,003.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.78 : 1,928.07 = 670.14 : x
  2. Step 2: Convert to fraction form
    1,287.78/1,928.07 = 670.14/x
  3. Step 3: Cross multiply
    1,287.78x = 1,928.07 × 670.14
  4. Step 4: Simplify right side
    1,287.78x = 1,292,076.83
  5. Step 5: Solve for x
    x = 1,292,076.83/1,287.78
  6. Step 6: Final answer
    x = 1,003.34

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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.