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Finding the Fourth Proportional to 115.72, 159.72 and 78.89

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Solution

The fourth proportional to 115.72, 159.72 and 78.89 is: 108.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.72 : 159.72 = 78.89 : x
  2. Step 2: Convert to fraction form
    115.72/159.72 = 78.89/x
  3. Step 3: Cross multiply
    115.72x = 159.72 × 78.89
  4. Step 4: Simplify right side
    115.72x = 12,600.11
  5. Step 5: Solve for x
    x = 12,600.11/115.72
  6. Step 6: Final answer
    x = 108.89

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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.