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Finding the Fourth Proportional to 42.78, 63.78 and 39.72

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Solution

The fourth proportional to 42.78, 63.78 and 39.72 is: 59.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.78 : 63.78 = 39.72 : x
  2. Step 2: Convert to fraction form
    42.78/63.78 = 39.72/x
  3. Step 3: Cross multiply
    42.78x = 63.78 × 39.72
  4. Step 4: Simplify right side
    42.78x = 2,533.34
  5. Step 5: Solve for x
    x = 2,533.34/42.78
  6. Step 6: Final answer
    x = 59.22

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.