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Finding the Fourth Proportional to 208.56, 312.96 and 85.13

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Solution

The fourth proportional to 208.56, 312.96 and 85.13 is: 127.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.56 : 312.96 = 85.13 : x
  2. Step 2: Convert to fraction form
    208.56/312.96 = 85.13/x
  3. Step 3: Cross multiply
    208.56x = 312.96 × 85.13
  4. Step 4: Simplify right side
    208.56x = 26,642.28
  5. Step 5: Solve for x
    x = 26,642.28/208.56
  6. Step 6: Final answer
    x = 127.74

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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.