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Finding the Fourth Proportional to 1,388.80, 2,080.40 and 867.20

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Solution

The fourth proportional to 1,388.80, 2,080.40 and 867.20 is: 1,299.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,388.80 : 2,080.40 = 867.20 : x
  2. Step 2: Convert to fraction form
    1,388.80/2,080.40 = 867.20/x
  3. Step 3: Cross multiply
    1,388.80x = 2,080.40 × 867.20
  4. Step 4: Simplify right side
    1,388.80x = 1,804,122.88
  5. Step 5: Solve for x
    x = 1,804,122.88/1,388.80
  6. Step 6: Final answer
    x = 1,299.05

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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.