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Finding the Fourth Proportional to 167.78, 231.80 and 121.40

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Solution

The fourth proportional to 167.78, 231.80 and 121.40 is: 167.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    167.78 : 231.80 = 121.40 : x
  2. Step 2: Convert to fraction form
    167.78/231.80 = 121.40/x
  3. Step 3: Cross multiply
    167.78x = 231.80 × 121.40
  4. Step 4: Simplify right side
    167.78x = 28,140.52
  5. Step 5: Solve for x
    x = 28,140.52/167.78
  6. Step 6: Final answer
    x = 167.72

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.