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Finding the Fourth Proportional to 78.39, 117 and 68.13

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Solution

The fourth proportional to 78.39, 117 and 68.13 is: 101.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.39 : 117 = 68.13 : x
  2. Step 2: Convert to fraction form
    78.39/117 = 68.13/x
  3. Step 3: Cross multiply
    78.39x = 117 × 68.13
  4. Step 4: Simplify right side
    78.39x = 7,971.21
  5. Step 5: Solve for x
    x = 7,971.21/78.39
  6. Step 6: Final answer
    x = 101.69

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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.