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Finding the Fourth Proportional to 85.14, 117.29 and 78.86

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Solution

The fourth proportional to 85.14, 117.29 and 78.86 is: 108.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.14 : 117.29 = 78.86 : x
  2. Step 2: Convert to fraction form
    85.14/117.29 = 78.86/x
  3. Step 3: Cross multiply
    85.14x = 117.29 × 78.86
  4. Step 4: Simplify right side
    85.14x = 9,248.51
  5. Step 5: Solve for x
    x = 9,248.51/85.14
  6. Step 6: Final answer
    x = 108.63

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.