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Finding the Fourth Proportional to 1,681.80, 2,521.20 and 861.09

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Solution

The fourth proportional to 1,681.80, 2,521.20 and 861.09 is: 1,290.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,681.80 : 2,521.20 = 861.09 : x
  2. Step 2: Convert to fraction form
    1,681.80/2,521.20 = 861.09/x
  3. Step 3: Cross multiply
    1,681.80x = 2,521.20 × 861.09
  4. Step 4: Simplify right side
    1,681.80x = 2,170,980.11
  5. Step 5: Solve for x
    x = 2,170,980.11/1,681.80
  6. Step 6: Final answer
    x = 1,290.87

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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.