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Finding the Fourth Proportional to 485.90, 728.84 and 139.23

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Solution

The fourth proportional to 485.90, 728.84 and 139.23 is: 208.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.90 : 728.84 = 139.23 : x
  2. Step 2: Convert to fraction form
    485.90/728.84 = 139.23/x
  3. Step 3: Cross multiply
    485.90x = 728.84 × 139.23
  4. Step 4: Simplify right side
    485.90x = 101,475.70
  5. Step 5: Solve for x
    x = 101,475.70/485.90
  6. Step 6: Final answer
    x = 208.84

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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.