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Finding the Fourth Proportional to 1,317.68, 1,818.60 and 820.40

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Solution

The fourth proportional to 1,317.68, 1,818.60 and 820.40 is: 1,132.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,317.68 : 1,818.60 = 820.40 : x
  2. Step 2: Convert to fraction form
    1,317.68/1,818.60 = 820.40/x
  3. Step 3: Cross multiply
    1,317.68x = 1,818.60 × 820.40
  4. Step 4: Simplify right side
    1,317.68x = 1,491,979.44
  5. Step 5: Solve for x
    x = 1,491,979.44/1,317.68
  6. Step 6: Final answer
    x = 1,132.28

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.