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Finding the Fourth Proportional to 1,008.78, 1,512.90 and 392.40

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Solution

The fourth proportional to 1,008.78, 1,512.90 and 392.40 is: 588.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,008.78 : 1,512.90 = 392.40 : x
  2. Step 2: Convert to fraction form
    1,008.78/1,512.90 = 392.40/x
  3. Step 3: Cross multiply
    1,008.78x = 1,512.90 × 392.40
  4. Step 4: Simplify right side
    1,008.78x = 593,661.96
  5. Step 5: Solve for x
    x = 593,661.96/1,008.78
  6. Step 6: Final answer
    x = 588.49

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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.