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Finding the Fourth Proportional to 42.69, 64.05 and 19.89

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Solution

The fourth proportional to 42.69, 64.05 and 19.89 is: 29.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.69 : 64.05 = 19.89 : x
  2. Step 2: Convert to fraction form
    42.69/64.05 = 19.89/x
  3. Step 3: Cross multiply
    42.69x = 64.05 × 19.89
  4. Step 4: Simplify right side
    42.69x = 1,273.95
  5. Step 5: Solve for x
    x = 1,273.95/42.69
  6. Step 6: Final answer
    x = 29.84

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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.