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Finding the Fourth Proportional to 485.85, 728.55 and 211.80

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Solution

The fourth proportional to 485.85, 728.55 and 211.80 is: 317.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.85 : 728.55 = 211.80 : x
  2. Step 2: Convert to fraction form
    485.85/728.55 = 211.80/x
  3. Step 3: Cross multiply
    485.85x = 728.55 × 211.80
  4. Step 4: Simplify right side
    485.85x = 154,306.89
  5. Step 5: Solve for x
    x = 154,306.89/485.85
  6. Step 6: Final answer
    x = 317.60

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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.