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Finding the Fourth Proportional to 64.20, 87.42 and 63.84

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Solution

The fourth proportional to 64.20, 87.42 and 63.84 is: 86.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    64.20 : 87.42 = 63.84 : x
  2. Step 2: Convert to fraction form
    64.20/87.42 = 63.84/x
  3. Step 3: Cross multiply
    64.20x = 87.42 × 63.84
  4. Step 4: Simplify right side
    64.20x = 5,580.89
  5. Step 5: Solve for x
    x = 5,580.89/64.20
  6. Step 6: Final answer
    x = 86.93

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Why These Related Problems?

These problems maintain the same ratio (1.36) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.