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Finding the Fourth Proportional to 485.50, 728.76 and 211.72

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Solution

The fourth proportional to 485.50, 728.76 and 211.72 is: 317.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.50 : 728.76 = 211.72 : x
  2. Step 2: Convert to fraction form
    485.50/728.76 = 211.72/x
  3. Step 3: Cross multiply
    485.50x = 728.76 × 211.72
  4. Step 4: Simplify right side
    485.50x = 154,293.07
  5. Step 5: Solve for x
    x = 154,293.07/485.50
  6. Step 6: Final answer
    x = 317.80

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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.