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Finding the Fourth Proportional to 85.12, 117.47 and 47.78

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Solution

The fourth proportional to 85.12, 117.47 and 47.78 is: 65.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.12 : 117.47 = 47.78 : x
  2. Step 2: Convert to fraction form
    85.12/117.47 = 47.78/x
  3. Step 3: Cross multiply
    85.12x = 117.47 × 47.78
  4. Step 4: Simplify right side
    85.12x = 5,612.48
  5. Step 5: Solve for x
    x = 5,612.48/85.12
  6. Step 6: Final answer
    x = 65.93

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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.