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Finding the Fourth Proportional to 42.78, 64.07 and 39.54

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Solution

The fourth proportional to 42.78, 64.07 and 39.54 is: 59.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.78 : 64.07 = 39.54 : x
  2. Step 2: Convert to fraction form
    42.78/64.07 = 39.54/x
  3. Step 3: Cross multiply
    42.78x = 64.07 × 39.54
  4. Step 4: Simplify right side
    42.78x = 2,533.13
  5. Step 5: Solve for x
    x = 2,533.13/42.78
  6. Step 6: Final answer
    x = 59.21

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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.