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Finding the Fourth Proportional to 137.40, 189.72 and 90.80

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Solution

The fourth proportional to 137.40, 189.72 and 90.80 is: 125.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    137.40 : 189.72 = 90.80 : x
  2. Step 2: Convert to fraction form
    137.40/189.72 = 90.80/x
  3. Step 3: Cross multiply
    137.40x = 189.72 × 90.80
  4. Step 4: Simplify right side
    137.40x = 17,226.58
  5. Step 5: Solve for x
    x = 17,226.58/137.40
  6. Step 6: Final answer
    x = 125.38

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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.