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Finding the Fourth Proportional to 111.51, 167.40 and 85.80

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Solution

The fourth proportional to 111.51, 167.40 and 85.80 is: 128.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.51 : 167.40 = 85.80 : x
  2. Step 2: Convert to fraction form
    111.51/167.40 = 85.80/x
  3. Step 3: Cross multiply
    111.51x = 167.40 × 85.80
  4. Step 4: Simplify right side
    111.51x = 14,362.92
  5. Step 5: Solve for x
    x = 14,362.92/111.51
  6. Step 6: Final answer
    x = 128.80

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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.