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Finding the Fourth Proportional to 78.90, 118.24 and 42.86

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Solution

The fourth proportional to 78.90, 118.24 and 42.86 is: 64.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.90 : 118.24 = 42.86 : x
  2. Step 2: Convert to fraction form
    78.90/118.24 = 42.86/x
  3. Step 3: Cross multiply
    78.90x = 118.24 × 42.86
  4. Step 4: Simplify right side
    78.90x = 5,067.77
  5. Step 5: Solve for x
    x = 5,067.77/78.90
  6. Step 6: Final answer
    x = 64.23

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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.