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Finding the Fourth Proportional to 78.25, 117.31 and 61.16

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Solution

The fourth proportional to 78.25, 117.31 and 61.16 is: 91.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.25 : 117.31 = 61.16 : x
  2. Step 2: Convert to fraction form
    78.25/117.31 = 61.16/x
  3. Step 3: Cross multiply
    78.25x = 117.31 × 61.16
  4. Step 4: Simplify right side
    78.25x = 7,174.93
  5. Step 5: Solve for x
    x = 7,174.93/78.25
  6. Step 6: Final answer
    x = 91.70

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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.