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Finding the Fourth Proportional to 90.70, 135.79 and 72.38

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Solution

The fourth proportional to 90.70, 135.79 and 72.38 is: 108.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.70 : 135.79 = 72.38 : x
  2. Step 2: Convert to fraction form
    90.70/135.79 = 72.38/x
  3. Step 3: Cross multiply
    90.70x = 135.79 × 72.38
  4. Step 4: Simplify right side
    90.70x = 9,827.44
  5. Step 5: Solve for x
    x = 9,827.44/90.70
  6. Step 6: Final answer
    x = 108.36

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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.