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Finding the Fourth Proportional to 121.64, 182.45 and 85.79

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Solution

The fourth proportional to 121.64, 182.45 and 85.79 is: 128.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.64 : 182.45 = 85.79 : x
  2. Step 2: Convert to fraction form
    121.64/182.45 = 85.79/x
  3. Step 3: Cross multiply
    121.64x = 182.45 × 85.79
  4. Step 4: Simplify right side
    121.64x = 15,653.06
  5. Step 5: Solve for x
    x = 15,653.06/121.64
  6. Step 6: Final answer
    x = 128.69

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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.