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Finding the Fourth Proportional to 208.78, 313.00 and 91.60

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Solution

The fourth proportional to 208.78, 313.00 and 91.60 is: 137.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.78 : 313.00 = 91.60 : x
  2. Step 2: Convert to fraction form
    208.78/313.00 = 91.60/x
  3. Step 3: Cross multiply
    208.78x = 313.00 × 91.60
  4. Step 4: Simplify right side
    208.78x = 28,669.79
  5. Step 5: Solve for x
    x = 28,669.79/208.78
  6. Step 6: Final answer
    x = 137.32

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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.