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Finding the Fourth Proportional to 810, 1,215.30 and 485.59

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Solution

The fourth proportional to 810, 1,215.30 and 485.59 is: 728.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    810 : 1,215.30 = 485.59 : x
  2. Step 2: Convert to fraction form
    810/1,215.30 = 485.59/x
  3. Step 3: Cross multiply
    810x = 1,215.30 × 485.59
  4. Step 4: Simplify right side
    810x = 590,137.53
  5. Step 5: Solve for x
    x = 590,137.53/810
  6. Step 6: Final answer
    x = 728.56

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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.