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Finding the Fourth Proportional to 72.53, 108.78 and 21.17

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Solution

The fourth proportional to 72.53, 108.78 and 21.17 is: 31.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.53 : 108.78 = 21.17 : x
  2. Step 2: Convert to fraction form
    72.53/108.78 = 21.17/x
  3. Step 3: Cross multiply
    72.53x = 108.78 × 21.17
  4. Step 4: Simplify right side
    72.53x = 2,302.77
  5. Step 5: Solve for x
    x = 2,302.77/72.53
  6. Step 6: Final answer
    x = 31.75

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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.