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Finding the Fourth Proportional to 1,222, 1,685.70 and 779.20

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Solution

The fourth proportional to 1,222, 1,685.70 and 779.20 is: 1,074.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,222 : 1,685.70 = 779.20 : x
  2. Step 2: Convert to fraction form
    1,222/1,685.70 = 779.20/x
  3. Step 3: Cross multiply
    1,222x = 1,685.70 × 779.20
  4. Step 4: Simplify right side
    1,222x = 1,313,497.44
  5. Step 5: Solve for x
    x = 1,313,497.44/1,222
  6. Step 6: Final answer
    x = 1,074.88

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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.