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Finding the Fourth Proportional to 1,218.21, 1,680.82 and 720.64

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Solution

The fourth proportional to 1,218.21, 1,680.82 and 720.64 is: 994.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.21 : 1,680.82 = 720.64 : x
  2. Step 2: Convert to fraction form
    1,218.21/1,680.82 = 720.64/x
  3. Step 3: Cross multiply
    1,218.21x = 1,680.82 × 720.64
  4. Step 4: Simplify right side
    1,218.21x = 1,211,266.12
  5. Step 5: Solve for x
    x = 1,211,266.12/1,218.21
  6. Step 6: Final answer
    x = 994.30

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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.