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Finding the Fourth Proportional to 85.99, 129.45 and 78.55

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Solution

The fourth proportional to 85.99, 129.45 and 78.55 is: 118.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.99 : 129.45 = 78.55 : x
  2. Step 2: Convert to fraction form
    85.99/129.45 = 78.55/x
  3. Step 3: Cross multiply
    85.99x = 129.45 × 78.55
  4. Step 4: Simplify right side
    85.99x = 10,168.30
  5. Step 5: Solve for x
    x = 10,168.30/85.99
  6. Step 6: Final answer
    x = 118.25

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.