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Finding the Fourth Proportional to 67.20, 100.72 and 64.80

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Solution

The fourth proportional to 67.20, 100.72 and 64.80 is: 97.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    67.20 : 100.72 = 64.80 : x
  2. Step 2: Convert to fraction form
    67.20/100.72 = 64.80/x
  3. Step 3: Cross multiply
    67.20x = 100.72 × 64.80
  4. Step 4: Simplify right side
    67.20x = 6,526.66
  5. Step 5: Solve for x
    x = 6,526.66/67.20
  6. Step 6: Final answer
    x = 97.12

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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.