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Finding the Fourth Proportional to 121.69, 182.46 and 78.40

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Solution

The fourth proportional to 121.69, 182.46 and 78.40 is: 117.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.69 : 182.46 = 78.40 : x
  2. Step 2: Convert to fraction form
    121.69/182.46 = 78.40/x
  3. Step 3: Cross multiply
    121.69x = 182.46 × 78.40
  4. Step 4: Simplify right side
    121.69x = 14,304.86
  5. Step 5: Solve for x
    x = 14,304.86/121.69
  6. Step 6: Final answer
    x = 117.55

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.