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Finding the Fourth Proportional to 90.65, 135.40 and 72.56

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Solution

The fourth proportional to 90.65, 135.40 and 72.56 is: 108.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.65 : 135.40 = 72.56 : x
  2. Step 2: Convert to fraction form
    90.65/135.40 = 72.56/x
  3. Step 3: Cross multiply
    90.65x = 135.40 × 72.56
  4. Step 4: Simplify right side
    90.65x = 9,824.62
  5. Step 5: Solve for x
    x = 9,824.62/90.65
  6. Step 6: Final answer
    x = 108.38

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.