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Finding the Fourth Proportional to 1,221.70, 1,685.79 and 697.90

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Solution

The fourth proportional to 1,221.70, 1,685.79 and 697.90 is: 963.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.70 : 1,685.79 = 697.90 : x
  2. Step 2: Convert to fraction form
    1,221.70/1,685.79 = 697.90/x
  3. Step 3: Cross multiply
    1,221.70x = 1,685.79 × 697.90
  4. Step 4: Simplify right side
    1,221.70x = 1,176,512.84
  5. Step 5: Solve for x
    x = 1,176,512.84/1,221.70
  6. Step 6: Final answer
    x = 963.01

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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.