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Finding the Fourth Proportional to 1,222.39, 1,686.63 and 780.85

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Solution

The fourth proportional to 1,222.39, 1,686.63 and 780.85 is: 1,077.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,222.39 : 1,686.63 = 780.85 : x
  2. Step 2: Convert to fraction form
    1,222.39/1,686.63 = 780.85/x
  3. Step 3: Cross multiply
    1,222.39x = 1,686.63 × 780.85
  4. Step 4: Simplify right side
    1,222.39x = 1,317,005.04
  5. Step 5: Solve for x
    x = 1,317,005.04/1,222.39
  6. Step 6: Final answer
    x = 1,077.40

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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.