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Finding the Fourth Proportional to 857.21, 1,285.85 and 309.20

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Solution

The fourth proportional to 857.21, 1,285.85 and 309.20 is: 463.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.21 : 1,285.85 = 309.20 : x
  2. Step 2: Convert to fraction form
    857.21/1,285.85 = 309.20/x
  3. Step 3: Cross multiply
    857.21x = 1,285.85 × 309.20
  4. Step 4: Simplify right side
    857.21x = 397,588.81
  5. Step 5: Solve for x
    x = 397,588.81/857.21
  6. Step 6: Final answer
    x = 463.82

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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.