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Finding the Fourth Proportional to 78.15, 117.24 and 61.11

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Solution

The fourth proportional to 78.15, 117.24 and 61.11 is: 91.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.15 : 117.24 = 61.11 : x
  2. Step 2: Convert to fraction form
    78.15/117.24 = 61.11/x
  3. Step 3: Cross multiply
    78.15x = 117.24 × 61.11
  4. Step 4: Simplify right side
    78.15x = 7,164.54
  5. Step 5: Solve for x
    x = 7,164.54/78.15
  6. Step 6: Final answer
    x = 91.68

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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.