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Finding the Fourth Proportional to 42.39, 63.51 and 21.80

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Solution

The fourth proportional to 42.39, 63.51 and 21.80 is: 32.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.39 : 63.51 = 21.80 : x
  2. Step 2: Convert to fraction form
    42.39/63.51 = 21.80/x
  3. Step 3: Cross multiply
    42.39x = 63.51 × 21.80
  4. Step 4: Simplify right side
    42.39x = 1,384.39
  5. Step 5: Solve for x
    x = 1,384.39/42.39
  6. Step 6: Final answer
    x = 32.66

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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.