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Finding the Fourth Proportional to 1,121.60, 1,681.27 and 428.11

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Solution

The fourth proportional to 1,121.60, 1,681.27 and 428.11 is: 641.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.60 : 1,681.27 = 428.11 : x
  2. Step 2: Convert to fraction form
    1,121.60/1,681.27 = 428.11/x
  3. Step 3: Cross multiply
    1,121.60x = 1,681.27 × 428.11
  4. Step 4: Simplify right side
    1,121.60x = 719,763.23
  5. Step 5: Solve for x
    x = 719,763.23/1,121.60
  6. Step 6: Final answer
    x = 641.73

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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.