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Finding the Fourth Proportional to 891.21, 1,336.43 and 428.88

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Solution

The fourth proportional to 891.21, 1,336.43 and 428.88 is: 643.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    891.21 : 1,336.43 = 428.88 : x
  2. Step 2: Convert to fraction form
    891.21/1,336.43 = 428.88/x
  3. Step 3: Cross multiply
    891.21x = 1,336.43 × 428.88
  4. Step 4: Simplify right side
    891.21x = 573,165.95
  5. Step 5: Solve for x
    x = 573,165.95/891.21
  6. Step 6: Final answer
    x = 643.13

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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.