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Finding the Fourth Proportional to 78.96, 108.96 and 49.86

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Solution

The fourth proportional to 78.96, 108.96 and 49.86 is: 68.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.96 : 108.96 = 49.86 : x
  2. Step 2: Convert to fraction form
    78.96/108.96 = 49.86/x
  3. Step 3: Cross multiply
    78.96x = 108.96 × 49.86
  4. Step 4: Simplify right side
    78.96x = 5,432.75
  5. Step 5: Solve for x
    x = 5,432.75/78.96
  6. Step 6: Final answer
    x = 68.80

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.