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Finding the Fourth Proportional to 1,390.84, 2,072.87 and 1,388.68

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Solution

The fourth proportional to 1,390.84, 2,072.87 and 1,388.68 is: 2,069.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.84 : 2,072.87 = 1,388.68 : x
  2. Step 2: Convert to fraction form
    1,390.84/2,072.87 = 1,388.68/x
  3. Step 3: Cross multiply
    1,390.84x = 2,072.87 × 1,388.68
  4. Step 4: Simplify right side
    1,390.84x = 2,878,553.11
  5. Step 5: Solve for x
    x = 2,878,553.11/1,390.84
  6. Step 6: Final answer
    x = 2,069.65

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.