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Finding the Fourth Proportional to 139.12, 208.64 and 90.34

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Solution

The fourth proportional to 139.12, 208.64 and 90.34 is: 135.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.12 : 208.64 = 90.34 : x
  2. Step 2: Convert to fraction form
    139.12/208.64 = 90.34/x
  3. Step 3: Cross multiply
    139.12x = 208.64 × 90.34
  4. Step 4: Simplify right side
    139.12x = 18,848.24
  5. Step 5: Solve for x
    x = 18,848.24/139.12
  6. Step 6: Final answer
    x = 135.48

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.