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Finding the Fourth Proportional to 115.72, 159.48 and 86.20

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Solution

The fourth proportional to 115.72, 159.48 and 86.20 is: 118.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.72 : 159.48 = 86.20 : x
  2. Step 2: Convert to fraction form
    115.72/159.48 = 86.20/x
  3. Step 3: Cross multiply
    115.72x = 159.48 × 86.20
  4. Step 4: Simplify right side
    115.72x = 13,747.18
  5. Step 5: Solve for x
    x = 13,747.18/115.72
  6. Step 6: Final answer
    x = 118.80

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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.