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Finding the Fourth Proportional to 1,390.21, 2,080.49 and 862.90

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Solution

The fourth proportional to 1,390.21, 2,080.49 and 862.90 is: 1,291.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.21 : 2,080.49 = 862.90 : x
  2. Step 2: Convert to fraction form
    1,390.21/2,080.49 = 862.90/x
  3. Step 3: Cross multiply
    1,390.21x = 2,080.49 × 862.90
  4. Step 4: Simplify right side
    1,390.21x = 1,795,257.01
  5. Step 5: Solve for x
    x = 1,795,257.01/1,390.21
  6. Step 6: Final answer
    x = 1,291.35

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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.