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Finding the Fourth Proportional to 78.55, 117.87 and 78.31

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Solution

The fourth proportional to 78.55, 117.87 and 78.31 is: 117.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.55 : 117.87 = 78.31 : x
  2. Step 2: Convert to fraction form
    78.55/117.87 = 78.31/x
  3. Step 3: Cross multiply
    78.55x = 117.87 × 78.31
  4. Step 4: Simplify right side
    78.55x = 9,230.40
  5. Step 5: Solve for x
    x = 9,230.40/78.55
  6. Step 6: Final answer
    x = 117.51

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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.