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Finding the Fourth Proportional to 111.80, 167.70 and 85.70

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Solution

The fourth proportional to 111.80, 167.70 and 85.70 is: 128.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.80 : 167.70 = 85.70 : x
  2. Step 2: Convert to fraction form
    111.80/167.70 = 85.70/x
  3. Step 3: Cross multiply
    111.80x = 167.70 × 85.70
  4. Step 4: Simplify right side
    111.80x = 14,371.89
  5. Step 5: Solve for x
    x = 14,371.89/111.80
  6. Step 6: Final answer
    x = 128.55

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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.