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Finding the Fourth Proportional to 115.20, 159 and 76.40

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Solution

The fourth proportional to 115.20, 159 and 76.40 is: 105.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.20 : 159 = 76.40 : x
  2. Step 2: Convert to fraction form
    115.20/159 = 76.40/x
  3. Step 3: Cross multiply
    115.20x = 159 × 76.40
  4. Step 4: Simplify right side
    115.20x = 12,147.60
  5. Step 5: Solve for x
    x = 12,147.60/115.20
  6. Step 6: Final answer
    x = 105.45

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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.