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Finding the Fourth Proportional to 85.70, 129.09 and 70.67

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Solution

The fourth proportional to 85.70, 129.09 and 70.67 is: 106.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.70 : 129.09 = 70.67 : x
  2. Step 2: Convert to fraction form
    85.70/129.09 = 70.67/x
  3. Step 3: Cross multiply
    85.70x = 129.09 × 70.67
  4. Step 4: Simplify right side
    85.70x = 9,122.79
  5. Step 5: Solve for x
    x = 9,122.79/85.70
  6. Step 6: Final answer
    x = 106.45

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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.