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Finding the Fourth Proportional to 1,218.94, 1,681.99 and 721.40

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Solution

The fourth proportional to 1,218.94, 1,681.99 and 721.40 is: 995.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.94 : 1,681.99 = 721.40 : x
  2. Step 2: Convert to fraction form
    1,218.94/1,681.99 = 721.40/x
  3. Step 3: Cross multiply
    1,218.94x = 1,681.99 × 721.40
  4. Step 4: Simplify right side
    1,218.94x = 1,213,380.08
  5. Step 5: Solve for x
    x = 1,213,380.08/1,218.94
  6. Step 6: Final answer
    x = 995.44

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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.