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Finding the Fourth Proportional to 123.78, 169.70 and 121.88

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Solution

The fourth proportional to 123.78, 169.70 and 121.88 is: 167.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.78 : 169.70 = 121.88 : x
  2. Step 2: Convert to fraction form
    123.78/169.70 = 121.88/x
  3. Step 3: Cross multiply
    123.78x = 169.70 × 121.88
  4. Step 4: Simplify right side
    123.78x = 20,683.04
  5. Step 5: Solve for x
    x = 20,683.04/123.78
  6. Step 6: Final answer
    x = 167.10

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.