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Finding the Fourth Proportional to 208.51, 287.79 and 138.69

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Solution

The fourth proportional to 208.51, 287.79 and 138.69 is: 191.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.51 : 287.79 = 138.69 : x
  2. Step 2: Convert to fraction form
    208.51/287.79 = 138.69/x
  3. Step 3: Cross multiply
    208.51x = 287.79 × 138.69
  4. Step 4: Simplify right side
    208.51x = 39,913.60
  5. Step 5: Solve for x
    x = 39,913.60/208.51
  6. Step 6: Final answer
    x = 191.42

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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.