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Finding the Fourth Proportional to 1,009.80, 1,390.50 and 861.84

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Solution

The fourth proportional to 1,009.80, 1,390.50 and 861.84 is: 1,186.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,009.80 : 1,390.50 = 861.84 : x
  2. Step 2: Convert to fraction form
    1,009.80/1,390.50 = 861.84/x
  3. Step 3: Cross multiply
    1,009.80x = 1,390.50 × 861.84
  4. Step 4: Simplify right side
    1,009.80x = 1,198,388.52
  5. Step 5: Solve for x
    x = 1,198,388.52/1,009.80
  6. Step 6: Final answer
    x = 1,186.76

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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.