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Finding the Fourth Proportional to 839.21, 1,158.20 and 485.15

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Solution

The fourth proportional to 839.21, 1,158.20 and 485.15 is: 669.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.21 : 1,158.20 = 485.15 : x
  2. Step 2: Convert to fraction form
    839.21/1,158.20 = 485.15/x
  3. Step 3: Cross multiply
    839.21x = 1,158.20 × 485.15
  4. Step 4: Simplify right side
    839.21x = 561,896.15
  5. Step 5: Solve for x
    x = 561,896.15/839.21
  6. Step 6: Final answer
    x = 669.55

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.