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Finding the Fourth Proportional to 42.40, 63.78 and 39.07

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Solution

The fourth proportional to 42.40, 63.78 and 39.07 is: 58.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.40 : 63.78 = 39.07 : x
  2. Step 2: Convert to fraction form
    42.40/63.78 = 39.07/x
  3. Step 3: Cross multiply
    42.40x = 63.78 × 39.07
  4. Step 4: Simplify right side
    42.40x = 2,491.88
  5. Step 5: Solve for x
    x = 2,491.88/42.40
  6. Step 6: Final answer
    x = 58.77

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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.