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Finding the Fourth Proportional to 1,220.80, 1,683.36 and 778

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Solution

The fourth proportional to 1,220.80, 1,683.36 and 778 is: 1,072.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,220.80 : 1,683.36 = 778 : x
  2. Step 2: Convert to fraction form
    1,220.80/1,683.36 = 778/x
  3. Step 3: Cross multiply
    1,220.80x = 1,683.36 × 778
  4. Step 4: Simplify right side
    1,220.80x = 1,309,654.08
  5. Step 5: Solve for x
    x = 1,309,654.08/1,220.80
  6. Step 6: Final answer
    x = 1,072.78

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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.