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Finding the Fourth Proportional to 857.21, 1,285.67 and 280.08

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Solution

The fourth proportional to 857.21, 1,285.67 and 280.08 is: 420.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.21 : 1,285.67 = 280.08 : x
  2. Step 2: Convert to fraction form
    857.21/1,285.67 = 280.08/x
  3. Step 3: Cross multiply
    857.21x = 1,285.67 × 280.08
  4. Step 4: Simplify right side
    857.21x = 360,090.45
  5. Step 5: Solve for x
    x = 360,090.45/857.21
  6. Step 6: Final answer
    x = 420.07

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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.