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Finding the Fourth Proportional to 208, 287.12 and 139.20

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Solution

The fourth proportional to 208, 287.12 and 139.20 is: 192.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    208 : 287.12 = 139.20 : x
  2. Step 2: Convert to fraction form
    208/287.12 = 139.20/x
  3. Step 3: Cross multiply
    208x = 287.12 × 139.20
  4. Step 4: Simplify right side
    208x = 39,967.10
  5. Step 5: Solve for x
    x = 39,967.10/208
  6. Step 6: Final answer
    x = 192.15

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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.