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Finding the Fourth Proportional to 89.40, 133.80 and 72

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Solution

The fourth proportional to 89.40, 133.80 and 72 is: 107.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.40 : 133.80 = 72 : x
  2. Step 2: Convert to fraction form
    89.40/133.80 = 72/x
  3. Step 3: Cross multiply
    89.40x = 133.80 × 72
  4. Step 4: Simplify right side
    89.40x = 9,633.60
  5. Step 5: Solve for x
    x = 9,633.60/89.40
  6. Step 6: Final answer
    x = 107.76

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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.