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Finding the Fourth Proportional to 1,387.63, 2,080.64 and 657.20

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Solution

The fourth proportional to 1,387.63, 2,080.64 and 657.20 is: 985.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.63 : 2,080.64 = 657.20 : x
  2. Step 2: Convert to fraction form
    1,387.63/2,080.64 = 657.20/x
  3. Step 3: Cross multiply
    1,387.63x = 2,080.64 × 657.20
  4. Step 4: Simplify right side
    1,387.63x = 1,367,396.61
  5. Step 5: Solve for x
    x = 1,367,396.61/1,387.63
  6. Step 6: Final answer
    x = 985.42

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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.