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Finding the Fourth Proportional to 138.95, 208.51 and 57.80

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Solution

The fourth proportional to 138.95, 208.51 and 57.80 is: 86.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.95 : 208.51 = 57.80 : x
  2. Step 2: Convert to fraction form
    138.95/208.51 = 57.80/x
  3. Step 3: Cross multiply
    138.95x = 208.51 × 57.80
  4. Step 4: Simplify right side
    138.95x = 12,051.88
  5. Step 5: Solve for x
    x = 12,051.88/138.95
  6. Step 6: Final answer
    x = 86.74

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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.