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Finding the Fourth Proportional to 208.95, 313.56 and 87.21

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Solution

The fourth proportional to 208.95, 313.56 and 87.21 is: 130.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.95 : 313.56 = 87.21 : x
  2. Step 2: Convert to fraction form
    208.95/313.56 = 87.21/x
  3. Step 3: Cross multiply
    208.95x = 313.56 × 87.21
  4. Step 4: Simplify right side
    208.95x = 27,345.57
  5. Step 5: Solve for x
    x = 27,345.57/208.95
  6. Step 6: Final answer
    x = 130.87

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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.