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Finding the Fourth Proportional to 121.40, 167.58 and 77.79

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Solution

The fourth proportional to 121.40, 167.58 and 77.79 is: 107.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.40 : 167.58 = 77.79 : x
  2. Step 2: Convert to fraction form
    121.40/167.58 = 77.79/x
  3. Step 3: Cross multiply
    121.40x = 167.58 × 77.79
  4. Step 4: Simplify right side
    121.40x = 13,036.05
  5. Step 5: Solve for x
    x = 13,036.05/121.40
  6. Step 6: Final answer
    x = 107.39

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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.