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Finding the Fourth Proportional to 139.01, 208.40 and 78.23

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Solution

The fourth proportional to 139.01, 208.40 and 78.23 is: 117.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.01 : 208.40 = 78.23 : x
  2. Step 2: Convert to fraction form
    139.01/208.40 = 78.23/x
  3. Step 3: Cross multiply
    139.01x = 208.40 × 78.23
  4. Step 4: Simplify right side
    139.01x = 16,302.74
  5. Step 5: Solve for x
    x = 16,302.74/139.01
  6. Step 6: Final answer
    x = 117.28

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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.