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Finding the Fourth Proportional to 78.67, 117.89 and 78.30

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Solution

The fourth proportional to 78.67, 117.89 and 78.30 is: 117.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.67 : 117.89 = 78.30 : x
  2. Step 2: Convert to fraction form
    78.67/117.89 = 78.30/x
  3. Step 3: Cross multiply
    78.67x = 117.89 × 78.30
  4. Step 4: Simplify right side
    78.67x = 9,230.69
  5. Step 5: Solve for x
    x = 9,230.69/78.67
  6. Step 6: Final answer
    x = 117.33

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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.