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Finding the Fourth Proportional to 63.21, 87.19 and 39.89

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Solution

The fourth proportional to 63.21, 87.19 and 39.89 is: 55.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    63.21 : 87.19 = 39.89 : x
  2. Step 2: Convert to fraction form
    63.21/87.19 = 39.89/x
  3. Step 3: Cross multiply
    63.21x = 87.19 × 39.89
  4. Step 4: Simplify right side
    63.21x = 3,477.57
  5. Step 5: Solve for x
    x = 3,477.57/63.21
  6. Step 6: Final answer
    x = 55.02

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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.