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Finding the Fourth Proportional to 139.78, 192.86 and 90.65

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Solution

The fourth proportional to 139.78, 192.86 and 90.65 is: 125.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.78 : 192.86 = 90.65 : x
  2. Step 2: Convert to fraction form
    139.78/192.86 = 90.65/x
  3. Step 3: Cross multiply
    139.78x = 192.86 × 90.65
  4. Step 4: Simplify right side
    139.78x = 17,482.76
  5. Step 5: Solve for x
    x = 17,482.76/139.78
  6. Step 6: Final answer
    x = 125.07

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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.