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Finding the Fourth Proportional to 42.66, 63.95 and 21.22

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Solution

The fourth proportional to 42.66, 63.95 and 21.22 is: 31.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.66 : 63.95 = 21.22 : x
  2. Step 2: Convert to fraction form
    42.66/63.95 = 21.22/x
  3. Step 3: Cross multiply
    42.66x = 63.95 × 21.22
  4. Step 4: Simplify right side
    42.66x = 1,357.02
  5. Step 5: Solve for x
    x = 1,357.02/42.66
  6. Step 6: Final answer
    x = 31.81

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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.