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Finding the Fourth Proportional to 72.91, 109.36 and 18.80

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Solution

The fourth proportional to 72.91, 109.36 and 18.80 is: 28.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.91 : 109.36 = 18.80 : x
  2. Step 2: Convert to fraction form
    72.91/109.36 = 18.80/x
  3. Step 3: Cross multiply
    72.91x = 109.36 × 18.80
  4. Step 4: Simplify right side
    72.91x = 2,056.34
  5. Step 5: Solve for x
    x = 2,056.34/72.91
  6. Step 6: Final answer
    x = 28.20

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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.