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Finding the Fourth Proportional to 78.11, 117.29 and 53.81

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Solution

The fourth proportional to 78.11, 117.29 and 53.81 is: 80.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.11 : 117.29 = 53.81 : x
  2. Step 2: Convert to fraction form
    78.11/117.29 = 53.81/x
  3. Step 3: Cross multiply
    78.11x = 117.29 × 53.81
  4. Step 4: Simplify right side
    78.11x = 6,311.37
  5. Step 5: Solve for x
    x = 6,311.37/78.11
  6. Step 6: Final answer
    x = 80.80

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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.