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Finding the Fourth Proportional to 1,221.96, 1,686.36 and 780.24

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Solution

The fourth proportional to 1,221.96, 1,686.36 and 780.24 is: 1,076.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.96 : 1,686.36 = 780.24 : x
  2. Step 2: Convert to fraction form
    1,221.96/1,686.36 = 780.24/x
  3. Step 3: Cross multiply
    1,221.96x = 1,686.36 × 780.24
  4. Step 4: Simplify right side
    1,221.96x = 1,315,765.53
  5. Step 5: Solve for x
    x = 1,315,765.53/1,221.96
  6. Step 6: Final answer
    x = 1,076.77

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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.