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Finding the Fourth Proportional to 90.80, 136 and 72.64

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Solution

The fourth proportional to 90.80, 136 and 72.64 is: 108.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.80 : 136 = 72.64 : x
  2. Step 2: Convert to fraction form
    90.80/136 = 72.64/x
  3. Step 3: Cross multiply
    90.80x = 136 × 72.64
  4. Step 4: Simplify right side
    90.80x = 9,879.04
  5. Step 5: Solve for x
    x = 9,879.04/90.80
  6. Step 6: Final answer
    x = 108.80

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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.