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Finding the Fourth Proportional to 208.70, 287.90 and 121.31

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Solution

The fourth proportional to 208.70, 287.90 and 121.31 is: 167.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.70 : 287.90 = 121.31 : x
  2. Step 2: Convert to fraction form
    208.70/287.90 = 121.31/x
  3. Step 3: Cross multiply
    208.70x = 287.90 × 121.31
  4. Step 4: Simplify right side
    208.70x = 34,925.26
  5. Step 5: Solve for x
    x = 34,925.26/208.70
  6. Step 6: Final answer
    x = 167.35

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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.