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Finding the Fourth Proportional to 431.88, 648 and 139.50

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Solution

The fourth proportional to 431.88, 648 and 139.50 is: 209.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.88 : 648 = 139.50 : x
  2. Step 2: Convert to fraction form
    431.88/648 = 139.50/x
  3. Step 3: Cross multiply
    431.88x = 648 × 139.50
  4. Step 4: Simplify right side
    431.88x = 90,396
  5. Step 5: Solve for x
    x = 90,396/431.88
  6. Step 6: Final answer
    x = 209.31

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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.