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Finding the Fourth Proportional to 1,221.35, 1,685.37 and 717.15

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Solution

The fourth proportional to 1,221.35, 1,685.37 and 717.15 is: 989.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.35 : 1,685.37 = 717.15 : x
  2. Step 2: Convert to fraction form
    1,221.35/1,685.37 = 717.15/x
  3. Step 3: Cross multiply
    1,221.35x = 1,685.37 × 717.15
  4. Step 4: Simplify right side
    1,221.35x = 1,208,659.51
  5. Step 5: Solve for x
    x = 1,208,659.51/1,221.35
  6. Step 6: Final answer
    x = 989.61

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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.