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Finding the Fourth Proportional to 78.69, 117.79 and 76.65

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Solution

The fourth proportional to 78.69, 117.79 and 76.65 is: 114.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.69 : 117.79 = 76.65 : x
  2. Step 2: Convert to fraction form
    78.69/117.79 = 76.65/x
  3. Step 3: Cross multiply
    78.69x = 117.79 × 76.65
  4. Step 4: Simplify right side
    78.69x = 9,028.60
  5. Step 5: Solve for x
    x = 9,028.60/78.69
  6. Step 6: Final answer
    x = 114.74

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.