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Finding the Fourth Proportional to 890.80, 1,336.20 and 428.47

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Solution

The fourth proportional to 890.80, 1,336.20 and 428.47 is: 642.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    890.80 : 1,336.20 = 428.47 : x
  2. Step 2: Convert to fraction form
    890.80/1,336.20 = 428.47/x
  3. Step 3: Cross multiply
    890.80x = 1,336.20 × 428.47
  4. Step 4: Simplify right side
    890.80x = 572,521.61
  5. Step 5: Solve for x
    x = 572,521.61/890.80
  6. Step 6: Final answer
    x = 642.71

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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.