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Finding the Fourth Proportional to 78.66, 117.39 and 77.64

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Solution

The fourth proportional to 78.66, 117.39 and 77.64 is: 115.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.66 : 117.39 = 77.64 : x
  2. Step 2: Convert to fraction form
    78.66/117.39 = 77.64/x
  3. Step 3: Cross multiply
    78.66x = 117.39 × 77.64
  4. Step 4: Simplify right side
    78.66x = 9,114.16
  5. Step 5: Solve for x
    x = 9,114.16/78.66
  6. Step 6: Final answer
    x = 115.87

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.