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Finding the Fourth Proportional to 42.59, 63.86 and 21.21

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Solution

The fourth proportional to 42.59, 63.86 and 21.21 is: 31.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.59 : 63.86 = 21.21 : x
  2. Step 2: Convert to fraction form
    42.59/63.86 = 21.21/x
  3. Step 3: Cross multiply
    42.59x = 63.86 × 21.21
  4. Step 4: Simplify right side
    42.59x = 1,354.36
  5. Step 5: Solve for x
    x = 1,354.36/42.59
  6. Step 6: Final answer
    x = 31.80

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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.