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Finding the Fourth Proportional to 100.90, 139.43 and 78.83

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Solution

The fourth proportional to 100.90, 139.43 and 78.83 is: 108.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.90 : 139.43 = 78.83 : x
  2. Step 2: Convert to fraction form
    100.90/139.43 = 78.83/x
  3. Step 3: Cross multiply
    100.90x = 139.43 × 78.83
  4. Step 4: Simplify right side
    100.90x = 10,991.27
  5. Step 5: Solve for x
    x = 10,991.27/100.90
  6. Step 6: Final answer
    x = 108.93

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.