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Finding the Fourth Proportional to 121.50, 167.70 and 69.78

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Solution

The fourth proportional to 121.50, 167.70 and 69.78 is: 96.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.50 : 167.70 = 69.78 : x
  2. Step 2: Convert to fraction form
    121.50/167.70 = 69.78/x
  3. Step 3: Cross multiply
    121.50x = 167.70 × 69.78
  4. Step 4: Simplify right side
    121.50x = 11,702.11
  5. Step 5: Solve for x
    x = 11,702.11/121.50
  6. Step 6: Final answer
    x = 96.31

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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.