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Finding the Fourth Proportional to 485.80, 728.64 and 139.16

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Solution

The fourth proportional to 485.80, 728.64 and 139.16 is: 208.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.80 : 728.64 = 139.16 : x
  2. Step 2: Convert to fraction form
    485.80/728.64 = 139.16/x
  3. Step 3: Cross multiply
    485.80x = 728.64 × 139.16
  4. Step 4: Simplify right side
    485.80x = 101,397.54
  5. Step 5: Solve for x
    x = 101,397.54/485.80
  6. Step 6: Final answer
    x = 208.72

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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.