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Finding the Fourth Proportional to 1,428.75, 2,139.90 and 769.45

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Solution

The fourth proportional to 1,428.75, 2,139.90 and 769.45 is: 1,152.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,428.75 : 2,139.90 = 769.45 : x
  2. Step 2: Convert to fraction form
    1,428.75/2,139.90 = 769.45/x
  3. Step 3: Cross multiply
    1,428.75x = 2,139.90 × 769.45
  4. Step 4: Simplify right side
    1,428.75x = 1,646,546.06
  5. Step 5: Solve for x
    x = 1,646,546.06/1,428.75
  6. Step 6: Final answer
    x = 1,152.44

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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.