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Finding the Fourth Proportional to 828.21, 1,242.30 and 280.40

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Solution

The fourth proportional to 828.21, 1,242.30 and 280.40 is: 420.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    828.21 : 1,242.30 = 280.40 : x
  2. Step 2: Convert to fraction form
    828.21/1,242.30 = 280.40/x
  3. Step 3: Cross multiply
    828.21x = 1,242.30 × 280.40
  4. Step 4: Simplify right side
    828.21x = 348,335.76
  5. Step 5: Solve for x
    x = 348,335.76/828.21
  6. Step 6: Final answer
    x = 420.59

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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.