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Finding the Fourth Proportional to 78.49, 117.74 and 76.69

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Solution

The fourth proportional to 78.49, 117.74 and 76.69 is: 115.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.49 : 117.74 = 76.69 : x
  2. Step 2: Convert to fraction form
    78.49/117.74 = 76.69/x
  3. Step 3: Cross multiply
    78.49x = 117.74 × 76.69
  4. Step 4: Simplify right side
    78.49x = 9,029.10
  5. Step 5: Solve for x
    x = 9,029.10/78.49
  6. Step 6: Final answer
    x = 115.04

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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.