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Finding the Fourth Proportional to 42.75, 64.17 and 21.42

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Solution

The fourth proportional to 42.75, 64.17 and 21.42 is: 32.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.75 : 64.17 = 21.42 : x
  2. Step 2: Convert to fraction form
    42.75/64.17 = 21.42/x
  3. Step 3: Cross multiply
    42.75x = 64.17 × 21.42
  4. Step 4: Simplify right side
    42.75x = 1,374.52
  5. Step 5: Solve for x
    x = 1,374.52/42.75
  6. Step 6: Final answer
    x = 32.15

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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.