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Finding the Fourth Proportional to 1,221.44, 1,685.57 and 661.90

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Solution

The fourth proportional to 1,221.44, 1,685.57 and 661.90 is: 913.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.44 : 1,685.57 = 661.90 : x
  2. Step 2: Convert to fraction form
    1,221.44/1,685.57 = 661.90/x
  3. Step 3: Cross multiply
    1,221.44x = 1,685.57 × 661.90
  4. Step 4: Simplify right side
    1,221.44x = 1,115,678.78
  5. Step 5: Solve for x
    x = 1,115,678.78/1,221.44
  6. Step 6: Final answer
    x = 913.41

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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.