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Finding the Fourth Proportional to 139.15, 191.73 and 99.78

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Solution

The fourth proportional to 139.15, 191.73 and 99.78 is: 137.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.15 : 191.73 = 99.78 : x
  2. Step 2: Convert to fraction form
    139.15/191.73 = 99.78/x
  3. Step 3: Cross multiply
    139.15x = 191.73 × 99.78
  4. Step 4: Simplify right side
    139.15x = 19,130.47
  5. Step 5: Solve for x
    x = 19,130.47/139.15
  6. Step 6: Final answer
    x = 137.48

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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.