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Finding the Fourth Proportional to 208.56, 287.72 and 121.18

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Solution

The fourth proportional to 208.56, 287.72 and 121.18 is: 167.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.56 : 287.72 = 121.18 : x
  2. Step 2: Convert to fraction form
    208.56/287.72 = 121.18/x
  3. Step 3: Cross multiply
    208.56x = 287.72 × 121.18
  4. Step 4: Simplify right side
    208.56x = 34,865.91
  5. Step 5: Solve for x
    x = 34,865.91/208.56
  6. Step 6: Final answer
    x = 167.17

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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.