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Finding the Fourth Proportional to 1,223.12, 1,686.31 and 780.25

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Solution

The fourth proportional to 1,223.12, 1,686.31 and 780.25 is: 1,075.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,223.12 : 1,686.31 = 780.25 : x
  2. Step 2: Convert to fraction form
    1,223.12/1,686.31 = 780.25/x
  3. Step 3: Cross multiply
    1,223.12x = 1,686.31 × 780.25
  4. Step 4: Simplify right side
    1,223.12x = 1,315,737.21
  5. Step 5: Solve for x
    x = 1,315,737.21/1,223.12
  6. Step 6: Final answer
    x = 1,075.73

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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.