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Finding the Fourth Proportional to 78.64, 109 and 74.68

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Solution

The fourth proportional to 78.64, 109 and 74.68 is: 103.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.64 : 109 = 74.68 : x
  2. Step 2: Convert to fraction form
    78.64/109 = 74.68/x
  3. Step 3: Cross multiply
    78.64x = 109 × 74.68
  4. Step 4: Simplify right side
    78.64x = 8,140.12
  5. Step 5: Solve for x
    x = 8,140.12/78.64
  6. Step 6: Final answer
    x = 103.51

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.