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Finding the Fourth Proportional to 485.40, 728.10 and 211.20

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Solution

The fourth proportional to 485.40, 728.10 and 211.20 is: 316.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.40 : 728.10 = 211.20 : x
  2. Step 2: Convert to fraction form
    485.40/728.10 = 211.20/x
  3. Step 3: Cross multiply
    485.40x = 728.10 × 211.20
  4. Step 4: Simplify right side
    485.40x = 153,774.72
  5. Step 5: Solve for x
    x = 153,774.72/485.40
  6. Step 6: Final answer
    x = 316.80

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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.