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Finding the Fourth Proportional to 85.85, 118.40 and 56.78

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Solution

The fourth proportional to 85.85, 118.40 and 56.78 is: 78.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.85 : 118.40 = 56.78 : x
  2. Step 2: Convert to fraction form
    85.85/118.40 = 56.78/x
  3. Step 3: Cross multiply
    85.85x = 118.40 × 56.78
  4. Step 4: Simplify right side
    85.85x = 6,721.88
  5. Step 5: Solve for x
    x = 6,721.88/85.85
  6. Step 6: Final answer
    x = 78.30

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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.