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Finding the Fourth Proportional to 891.60, 1,337.40 and 821.20

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Solution

The fourth proportional to 891.60, 1,337.40 and 821.20 is: 1,231.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    891.60 : 1,337.40 = 821.20 : x
  2. Step 2: Convert to fraction form
    891.60/1,337.40 = 821.20/x
  3. Step 3: Cross multiply
    891.60x = 1,337.40 × 821.20
  4. Step 4: Simplify right side
    891.60x = 1,098,272.88
  5. Step 5: Solve for x
    x = 1,098,272.88/891.60
  6. Step 6: Final answer
    x = 1,231.80

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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.