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Finding the Fourth Proportional to 137.68, 189.95 and 85.21

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Solution

The fourth proportional to 137.68, 189.95 and 85.21 is: 117.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    137.68 : 189.95 = 85.21 : x
  2. Step 2: Convert to fraction form
    137.68/189.95 = 85.21/x
  3. Step 3: Cross multiply
    137.68x = 189.95 × 85.21
  4. Step 4: Simplify right side
    137.68x = 16,185.64
  5. Step 5: Solve for x
    x = 16,185.64/137.68
  6. Step 6: Final answer
    x = 117.56

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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.