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Finding the Fourth Proportional to 1,121.50, 1,681.71 and 428.03

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Solution

The fourth proportional to 1,121.50, 1,681.71 and 428.03 is: 641.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.50 : 1,681.71 = 428.03 : x
  2. Step 2: Convert to fraction form
    1,121.50/1,681.71 = 428.03/x
  3. Step 3: Cross multiply
    1,121.50x = 1,681.71 × 428.03
  4. Step 4: Simplify right side
    1,121.50x = 719,830.49
  5. Step 5: Solve for x
    x = 719,830.49/1,121.50
  6. Step 6: Final answer
    x = 641.85

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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.