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Finding the Fourth Proportional to 121.62, 167.76 and 77.90

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Solution

The fourth proportional to 121.62, 167.76 and 77.90 is: 107.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.62 : 167.76 = 77.90 : x
  2. Step 2: Convert to fraction form
    121.62/167.76 = 77.90/x
  3. Step 3: Cross multiply
    121.62x = 167.76 × 77.90
  4. Step 4: Simplify right side
    121.62x = 13,068.50
  5. Step 5: Solve for x
    x = 13,068.50/121.62
  6. Step 6: Final answer
    x = 107.45

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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.