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Finding the Fourth Proportional to 78.68, 117.70 and 67.28

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Solution

The fourth proportional to 78.68, 117.70 and 67.28 is: 100.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.68 : 117.70 = 67.28 : x
  2. Step 2: Convert to fraction form
    78.68/117.70 = 67.28/x
  3. Step 3: Cross multiply
    78.68x = 117.70 × 67.28
  4. Step 4: Simplify right side
    78.68x = 7,918.86
  5. Step 5: Solve for x
    x = 7,918.86/78.68
  6. Step 6: Final answer
    x = 100.65

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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.