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Finding the Fourth Proportional to 72.78, 109.17 and 30

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Solution

The fourth proportional to 72.78, 109.17 and 30 is: 45

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.78 : 109.17 = 30 : x
  2. Step 2: Convert to fraction form
    72.78/109.17 = 30/x
  3. Step 3: Cross multiply
    72.78x = 109.17 × 30
  4. Step 4: Simplify right side
    72.78x = 3,275.10
  5. Step 5: Solve for x
    x = 3,275.10/72.78
  6. Step 6: Final answer
    x = 45

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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.