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Finding the Fourth Proportional to 85.96, 129.67 and 85.78

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Solution

The fourth proportional to 85.96, 129.67 and 85.78 is: 129.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.96 : 129.67 = 85.78 : x
  2. Step 2: Convert to fraction form
    85.96/129.67 = 85.78/x
  3. Step 3: Cross multiply
    85.96x = 129.67 × 85.78
  4. Step 4: Simplify right side
    85.96x = 11,123.09
  5. Step 5: Solve for x
    x = 11,123.09/85.96
  6. Step 6: Final answer
    x = 129.40

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Double scale
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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.