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Finding the Fourth Proportional to 810.74, 1,216.05 and 420.63

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Solution

The fourth proportional to 810.74, 1,216.05 and 420.63 is: 630.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.74 : 1,216.05 = 420.63 : x
  2. Step 2: Convert to fraction form
    810.74/1,216.05 = 420.63/x
  3. Step 3: Cross multiply
    810.74x = 1,216.05 × 420.63
  4. Step 4: Simplify right side
    810.74x = 511,500.97
  5. Step 5: Solve for x
    x = 511,500.97/810.74
  6. Step 6: Final answer
    x = 630.90

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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.