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Finding the Fourth Proportional to 208.49, 312.78 and 64.21

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Solution

The fourth proportional to 208.49, 312.78 and 64.21 is: 96.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.49 : 312.78 = 64.21 : x
  2. Step 2: Convert to fraction form
    208.49/312.78 = 64.21/x
  3. Step 3: Cross multiply
    208.49x = 312.78 × 64.21
  4. Step 4: Simplify right side
    208.49x = 20,083.60
  5. Step 5: Solve for x
    x = 20,083.60/208.49
  6. Step 6: Final answer
    x = 96.33

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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.