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Finding the Fourth Proportional to 923.90, 1,387.20 and 559.40

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Solution

The fourth proportional to 923.90, 1,387.20 and 559.40 is: 839.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    923.90 : 1,387.20 = 559.40 : x
  2. Step 2: Convert to fraction form
    923.90/1,387.20 = 559.40/x
  3. Step 3: Cross multiply
    923.90x = 1,387.20 × 559.40
  4. Step 4: Simplify right side
    923.90x = 775,999.68
  5. Step 5: Solve for x
    x = 775,999.68/923.90
  6. Step 6: Final answer
    x = 839.92

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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.