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Finding the Fourth Proportional to 42.78, 64.19 and 19.95

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Solution

The fourth proportional to 42.78, 64.19 and 19.95 is: 29.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.78 : 64.19 = 19.95 : x
  2. Step 2: Convert to fraction form
    42.78/64.19 = 19.95/x
  3. Step 3: Cross multiply
    42.78x = 64.19 × 19.95
  4. Step 4: Simplify right side
    42.78x = 1,280.59
  5. Step 5: Solve for x
    x = 1,280.59/42.78
  6. Step 6: Final answer
    x = 29.93

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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.