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Finding the Fourth Proportional to 1,222.80, 1,687.74 and 780.36

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Solution

The fourth proportional to 1,222.80, 1,687.74 and 780.36 is: 1,077.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,222.80 : 1,687.74 = 780.36 : x
  2. Step 2: Convert to fraction form
    1,222.80/1,687.74 = 780.36/x
  3. Step 3: Cross multiply
    1,222.80x = 1,687.74 × 780.36
  4. Step 4: Simplify right side
    1,222.80x = 1,317,044.79
  5. Step 5: Solve for x
    x = 1,317,044.79/1,222.80
  6. Step 6: Final answer
    x = 1,077.07

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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.