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Finding the Fourth Proportional to 115.65, 159.47 and 78.84

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Solution

The fourth proportional to 115.65, 159.47 and 78.84 is: 108.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.65 : 159.47 = 78.84 : x
  2. Step 2: Convert to fraction form
    115.65/159.47 = 78.84/x
  3. Step 3: Cross multiply
    115.65x = 159.47 × 78.84
  4. Step 4: Simplify right side
    115.65x = 12,571.42
  5. Step 5: Solve for x
    x = 12,571.42/115.65
  6. Step 6: Final answer
    x = 108.70

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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.