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Finding the Fourth Proportional to 139.85, 192.85 and 90.64

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Solution

The fourth proportional to 139.85, 192.85 and 90.64 is: 124.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.85 : 192.85 = 90.64 : x
  2. Step 2: Convert to fraction form
    139.85/192.85 = 90.64/x
  3. Step 3: Cross multiply
    139.85x = 192.85 × 90.64
  4. Step 4: Simplify right side
    139.85x = 17,479.47
  5. Step 5: Solve for x
    x = 17,479.47/139.85
  6. Step 6: Final answer
    x = 124.99

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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.