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Finding the Fourth Proportional to 1,222.90, 1,686.89 and 780.30

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Solution

The fourth proportional to 1,222.90, 1,686.89 and 780.30 is: 1,076.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,222.90 : 1,686.89 = 780.30 : x
  2. Step 2: Convert to fraction form
    1,222.90/1,686.89 = 780.30/x
  3. Step 3: Cross multiply
    1,222.90x = 1,686.89 × 780.30
  4. Step 4: Simplify right side
    1,222.90x = 1,316,282.22
  5. Step 5: Solve for x
    x = 1,316,282.22/1,222.90
  6. Step 6: Final answer
    x = 1,076.36

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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.