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Finding the Fourth Proportional to 85.98, 129.18 and 70.78

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Solution

The fourth proportional to 85.98, 129.18 and 70.78 is: 106.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.98 : 129.18 = 70.78 : x
  2. Step 2: Convert to fraction form
    85.98/129.18 = 70.78/x
  3. Step 3: Cross multiply
    85.98x = 129.18 × 70.78
  4. Step 4: Simplify right side
    85.98x = 9,143.36
  5. Step 5: Solve for x
    x = 9,143.36/85.98
  6. Step 6: Final answer
    x = 106.34

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.