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Finding the Fourth Proportional to 121.70, 167.94 and 78.06

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Solution

The fourth proportional to 121.70, 167.94 and 78.06 is: 107.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.70 : 167.94 = 78.06 : x
  2. Step 2: Convert to fraction form
    121.70/167.94 = 78.06/x
  3. Step 3: Cross multiply
    121.70x = 167.94 × 78.06
  4. Step 4: Simplify right side
    121.70x = 13,109.40
  5. Step 5: Solve for x
    x = 13,109.40/121.70
  6. Step 6: Final answer
    x = 107.72

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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.