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Finding the Fourth Proportional to 85.11, 117.32 and 72.78

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Solution

The fourth proportional to 85.11, 117.32 and 72.78 is: 100.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.11 : 117.32 = 72.78 : x
  2. Step 2: Convert to fraction form
    85.11/117.32 = 72.78/x
  3. Step 3: Cross multiply
    85.11x = 117.32 × 72.78
  4. Step 4: Simplify right side
    85.11x = 8,538.19
  5. Step 5: Solve for x
    x = 8,538.19/85.11
  6. Step 6: Final answer
    x = 100.32

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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.