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Finding the Fourth Proportional to 139.72, 192.85 and 90

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Solution

The fourth proportional to 139.72, 192.85 and 90 is: 124.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.72 : 192.85 = 90 : x
  2. Step 2: Convert to fraction form
    139.72/192.85 = 90/x
  3. Step 3: Cross multiply
    139.72x = 192.85 × 90
  4. Step 4: Simplify right side
    139.72x = 17,356.05
  5. Step 5: Solve for x
    x = 17,356.05/139.72
  6. Step 6: Final answer
    x = 124.22

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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.