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Finding the Fourth Proportional to 1,222.09, 1,686.45 and 691

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Solution

The fourth proportional to 1,222.09, 1,686.45 and 691 is: 953.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,222.09 : 1,686.45 = 691 : x
  2. Step 2: Convert to fraction form
    1,222.09/1,686.45 = 691/x
  3. Step 3: Cross multiply
    1,222.09x = 1,686.45 × 691
  4. Step 4: Simplify right side
    1,222.09x = 1,165,336.95
  5. Step 5: Solve for x
    x = 1,165,336.95/1,222.09
  6. Step 6: Final answer
    x = 953.56

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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.