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Finding the Fourth Proportional to 78.16, 107.20 and 76.72

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Solution

The fourth proportional to 78.16, 107.20 and 76.72 is: 105.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.16 : 107.20 = 76.72 : x
  2. Step 2: Convert to fraction form
    78.16/107.20 = 76.72/x
  3. Step 3: Cross multiply
    78.16x = 107.20 × 76.72
  4. Step 4: Simplify right side
    78.16x = 8,224.38
  5. Step 5: Solve for x
    x = 8,224.38/78.16
  6. Step 6: Final answer
    x = 105.22

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.