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Finding the Fourth Proportional to 78.89, 118.43 and 42.85

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Solution

The fourth proportional to 78.89, 118.43 and 42.85 is: 64.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.89 : 118.43 = 42.85 : x
  2. Step 2: Convert to fraction form
    78.89/118.43 = 42.85/x
  3. Step 3: Cross multiply
    78.89x = 118.43 × 42.85
  4. Step 4: Simplify right side
    78.89x = 5,073.92
  5. Step 5: Solve for x
    x = 5,073.92/78.89
  6. Step 6: Final answer
    x = 64.32

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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.