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Finding the Fourth Proportional to 1,387.40, 2,079.28 and 656

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Solution

The fourth proportional to 1,387.40, 2,079.28 and 656 is: 983.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.40 : 2,079.28 = 656 : x
  2. Step 2: Convert to fraction form
    1,387.40/2,079.28 = 656/x
  3. Step 3: Cross multiply
    1,387.40x = 2,079.28 × 656
  4. Step 4: Simplify right side
    1,387.40x = 1,364,007.68
  5. Step 5: Solve for x
    x = 1,364,007.68/1,387.40
  6. Step 6: Final answer
    x = 983.14

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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.