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Finding the Fourth Proportional to 76.20, 105.21 and 72.45

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Solution

The fourth proportional to 76.20, 105.21 and 72.45 is: 100.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.20 : 105.21 = 72.45 : x
  2. Step 2: Convert to fraction form
    76.20/105.21 = 72.45/x
  3. Step 3: Cross multiply
    76.20x = 105.21 × 72.45
  4. Step 4: Simplify right side
    76.20x = 7,622.46
  5. Step 5: Solve for x
    x = 7,622.46/76.20
  6. Step 6: Final answer
    x = 100.03

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.